Search Results

Search found 16947 results on 678 pages for 'kernel programming'.

Page 485/678 | < Previous Page | 481 482 483 484 485 486 487 488 489 490 491 492  | Next Page >

  • C# Performance Pitfall – Interop Scenarios Change the Rules

    - by Reed
    C# and .NET, overall, really do have fantastic performance in my opinion.  That being said, the performance characteristics dramatically differ from native programming, and take some relearning if you’re used to doing performance optimization in most other languages, especially C, C++, and similar.  However, there are times when revisiting tricks learned in native code play a critical role in performance optimization in C#. I recently ran across a nasty scenario that illustrated to me how dangerous following any fixed rules for optimization can be… The rules in C# when optimizing code are very different than C or C++.  Often, they’re exactly backwards.  For example, in C and C++, lifting a variable out of loops in order to avoid memory allocations often can have huge advantages.  If some function within a call graph is allocating memory dynamically, and that gets called in a loop, it can dramatically slow down a routine. This can be a tricky bottleneck to track down, even with a profiler.  Looking at the memory allocation graph is usually the key for spotting this routine, as it’s often “hidden” deep in call graph.  For example, while optimizing some of my scientific routines, I ran into a situation where I had a loop similar to: for (i=0; i<numberToProcess; ++i) { // Do some work ProcessElement(element[i]); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This loop was at a fairly high level in the call graph, and often could take many hours to complete, depending on the input data.  As such, any performance optimization we could achieve would be greatly appreciated by our users. After a fair bit of profiling, I noticed that a couple of function calls down the call graph (inside of ProcessElement), there was some code that effectively was doing: // Allocate some data required DataStructure* data = new DataStructure(num); // Call into a subroutine that passed around and manipulated this data highly CallSubroutine(data); // Read and use some values from here double values = data->Foo; // Cleanup delete data; // ... return bar; Normally, if “DataStructure” was a simple data type, I could just allocate it on the stack.  However, it’s constructor, internally, allocated it’s own memory using new, so this wouldn’t eliminate the problem.  In this case, however, I could change the call signatures to allow the pointer to the data structure to be passed into ProcessElement and through the call graph, allowing the inner routine to reuse the same “data” memory instead of allocating.  At the highest level, my code effectively changed to something like: DataStructure* data = new DataStructure(numberToProcess); for (i=0; i<numberToProcess; ++i) { // Do some work ProcessElement(element[i], data); } delete data; Granted, this dramatically reduced the maintainability of the code, so it wasn’t something I wanted to do unless there was a significant benefit.  In this case, after profiling the new version, I found that it increased the overall performance dramatically – my main test case went from 35 minutes runtime down to 21 minutes.  This was such a significant improvement, I felt it was worth the reduction in maintainability. In C and C++, it’s generally a good idea (for performance) to: Reduce the number of memory allocations as much as possible, Use fewer, larger memory allocations instead of many smaller ones, and Allocate as high up the call stack as possible, and reuse memory I’ve seen many people try to make similar optimizations in C# code.  For good or bad, this is typically not a good idea.  The garbage collector in .NET completely changes the rules here. In C#, reallocating memory in a loop is not always a bad idea.  In this scenario, for example, I may have been much better off leaving the original code alone.  The reason for this is the garbage collector.  The GC in .NET is incredibly effective, and leaving the allocation deep inside the call stack has some huge advantages.  First and foremost, it tends to make the code more maintainable – passing around object references tends to couple the methods together more than necessary, and overall increase the complexity of the code.  This is something that should be avoided unless there is a significant reason.  Second, (unlike C and C++) memory allocation of a single object in C# is normally cheap and fast.  Finally, and most critically, there is a large advantage to having short lived objects.  If you lift a variable out of the loop and reuse the memory, its much more likely that object will get promoted to Gen1 (or worse, Gen2).  This can cause expensive compaction operations to be required, and also lead to (at least temporary) memory fragmentation as well as more costly collections later. As such, I’ve found that it’s often (though not always) faster to leave memory allocations where you’d naturally place them – deep inside of the call graph, inside of the loops.  This causes the objects to stay very short lived, which in turn increases the efficiency of the garbage collector, and can dramatically improve the overall performance of the routine as a whole. In C#, I tend to: Keep variable declarations in the tightest scope possible Declare and allocate objects at usage While this tends to cause some of the same goals (reducing unnecessary allocations, etc), the goal here is a bit different – it’s about keeping the objects rooted for as little time as possible in order to (attempt) to keep them completely in Gen0, or worst case, Gen1.  It also has the huge advantage of keeping the code very maintainable – objects are used and “released” as soon as possible, which keeps the code very clean.  It does, however, often have the side effect of causing more allocations to occur, but keeping the objects rooted for a much shorter time. Now – nowhere here am I suggesting that these rules are hard, fast rules that are always true.  That being said, my time spent optimizing over the years encourages me to naturally write code that follows the above guidelines, then profile and adjust as necessary.  In my current project, however, I ran across one of those nasty little pitfalls that’s something to keep in mind – interop changes the rules. In this case, I was dealing with an API that, internally, used some COM objects.  In this case, these COM objects were leading to native allocations (most likely C++) occurring in a loop deep in my call graph.  Even though I was writing nice, clean managed code, the normal managed code rules for performance no longer apply.  After profiling to find the bottleneck in my code, I realized that my inner loop, a innocuous looking block of C# code, was effectively causing a set of native memory allocations in every iteration.  This required going back to a “native programming” mindset for optimization.  Lifting these variables and reusing them took a 1:10 routine down to 0:20 – again, a very worthwhile improvement. Overall, the lessons here are: Always profile if you suspect a performance problem – don’t assume any rule is correct, or any code is efficient just because it looks like it should be Remember to check memory allocations when profiling, not just CPU cycles Interop scenarios often cause managed code to act very differently than “normal” managed code. Native code can be hidden very cleverly inside of managed wrappers

    Read the article

  • PostSharp, Obfuscation, and IL

    - by Simon Cooper
    Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day!

    Read the article

  • The Great Divorce

    - by BlackRabbitCoder
    I have a confession to make: I've been in an abusive relationship for more than 17 years now.  Yes, I am not ashamed to admit it, but I'm finally doing something about it. I met her in college, she was new and sexy and amazingly fast -- and I'd never met anything like her before.  Her style and her power captivated me and I couldn't wait to learn more about her.  I took a chance on her, and though I learned a lot from her -- and will always be grateful for my time with her -- I think it's time to move on. Her name was C++, and she so outshone my previous love, C, that any thoughts of going back evaporated in the heat of this new romance.  She promised me she'd be gentle and not hurt me the way C did.  She promised me she'd clean-up after herself better than C did.  She promised me she'd be less enigmatic and easier to keep happy than C was.  But I was deceived.  Oh sure, as far as truth goes, it wasn't a complete lie.  To some extent she was more fun, more powerful, safer, and easier to maintain.  But it just wasn't good enough -- or at least it's not good enough now. I loved C++, some part of me still does, it's my first-love of programming languages and I recognize its raw power, its blazing speed, and its improvements over its predecessor.  But with today's hardware, at speeds we could only dream to conceive of twenty years ago, that need for speed -- at the cost of all else -- has died, and that has left my feelings for C++ moribund. If I ever need to write an operating system or a device driver, then I might need that speed.  But 99% of the time I don't.  I'm a business-type programmer and chances are 90% of you are too, and even the ones who need speed at all costs may be surprised by how much you sacrifice for that.   That's not to say that I don't want my software to perform, and it's not to say that in the business world we don't care about speed or that our job is somehow less difficult or technical.  There's many times we write programs to handle millions of real-time updates or handle thousands of financial transactions or tracking trading algorithms where every second counts.  But if I choose to write my code in C++ purely for speed chances are I'll never notice the speed increase -- and equally true chances are it will be far more prone to crash and far less easy to maintain.  Nearly without fail, it's the macro-optimizations you need, not the micro-optimizations.  If I choose to write a O(n2) algorithm when I could have used a O(n) algorithm -- that can kill me.  If I choose to go to the database to load a piece of unchanging data every time instead of caching it on first load -- that too can kill me.  And if I cross the network multiple times for pieces of data instead of getting it all at once -- yes that can also kill me.  But choosing an overly powerful and dangerous mid-level language to squeeze out every last drop of performance will realistically not make stock orders process any faster, and more likely than not open up the system to more risk of crashes and resource leaks. And that's when my love for C++ began to die.  When I noticed that I didn't need that speed anymore.  That that speed was really kind of a lie.  Sure, I can be super efficient and pack bits in a byte instead of using separate boolean values.  Sure, I can use an unsigned char instead of an int.  But in the grand scheme of things it doesn't matter as much as you think it does.  The key is maintainability, and that's where C++ failed me.  I like to tell the other developers I work with that there's two levels of correctness in coding: Is it immediately correct? Will it stay correct? That is, you can hack together any piece of code and make it correct to satisfy a task at hand, but if a new developer can't come in tomorrow and make a fairly significant change to it without jeopardizing that correctness, it won't stay correct. Some people laugh at me when I say I now prefer maintainability over speed.  But that is exactly the point.  If you focus solely on speed you tend to produce code that is much harder to maintain over the long hall, and that's a load of technical debt most shops can't afford to carry and end up completely scrapping code before it's time.  When good code is written well for maintainability, though, it can be correct both now and in the future. And you know the best part is?  My new love is nearly as fast as C++, and in some cases even faster -- and better than that, I know C# will treat me right.  Her creators have poured hundreds of thousands of hours of time into making her the sexy beast she is today.  They made her easy to understand and not an enigmatic mess.  They made her consistent and not moody and amorphous.  And they made her perform as fast as I care to go by optimizing her both at compile time and a run-time. Her code is so elegant and easy on the eyes that I'm not worried where she will run to or what she'll pull behind my back.  She is powerful enough to handle all my tasks, fast enough to execute them with blazing speed, maintainable enough so that I can rely on even fairly new peers to modify my work, and rich enough to allow me to satisfy any need.  C# doesn't ask me to clean up her messes!  She cleans up after herself and she tries to make my life easier for me by taking on most of those optimization tasks C++ asked me to take upon myself.  Now, there are many of you who would say that I am the cause of my own grief, that it was my fault C++ didn't behave because I didn't pay enough attention to her.  That I alone caused the pain she inflicted on me.  And to some extent, you have a point.  But she was so high maintenance, requiring me to know every twist and turn of her vast and unrestrained power that any wrong term or bout of forgetfulness was met with painful reminders that she wasn't going to watch my back when I made a mistake.  But C#, she loves me when I'm good, and she loves me when I'm bad, and together we make beautiful code that is both fast and safe. So that's why I'm leaving C++ behind.  She says she's changing for me, but I have no interest in what C++0x may bring.  Oh, I'll still keep in touch, and maybe I'll see her now and again when she brings her problems to my door and asks for some attention -- for I always have a soft spot for her, you see.  But she's out of my house now.  I have three kids and a dog and a cat, and all require me to clean up after them, why should I have to clean up after my programming language as well?

    Read the article

  • Christmas in the Clouds

    - by andrewbrust
    I have been spending the last 2 weeks immersing myself in a number of Windows Azure and SQL Azure technologies.  And in setting up a new business (I’ll speak more about that in the future), I have also become a customer of Microsoft’s BPOS (Business Productivity Online Services).  In short, it has been a fortnight of Microsoft cloud computing. On the Azure side, I’ve looked, of course, at Web Roles and Worker Roles.  But I’ve also looked at Azure Storage’s REST API (including coding to it directly), I’ve looked at Azure Drive and the new VM Role; I’ve looked quite a bit at SQL Azure (including the project “Houston” Silverlight UI) and I’ve looked at SQL Azure labs’ OData service too. I’ve also looked at DataMarket and its integration with both PowerPivot and native Excel.  Then there’s AppFabric Caching, SQL Azure Reporting (what I could learn of it) and the Visual Studio tooling for Azure, including the storage of certificate-based credentials.  And to round it out with some user stuff, on the BPOS side, I’ve been working with Exchange Online, SharePoint Online and LiveMeeting. I have to say I like a lot of what I’ve been seeing.  Azure’s not perfect, and BPOS certainly isn’t either.  But there’s good stuff in all these products, and there’s a lot of value. Azure Goes Deep Most people know that Web and Worker roles put the platform in charge of spinning virtual machines up and down, and keeping them up to date. But you can go way beyond that now.  The still-in-beta VM Role gives you the power to craft the machine (much as does Amazon’s EC2), though it takes away the platform’s self-managing attributes.  It still spins instances up and down, making drive storage non-durable, but Azure Drive gives you the ability to store VHD files as blobs and mount them as virtual hard drives that are readable and writeable.  Whether with Azure Storage or SQL Azure, Azure does data.  And OData is everywhere.  Azure Table Storage supports an OData Interface.  So does SQL Azure and so does DataMarket (the former project “Dallas”).  That means that Azure data repositories aren’t just straightforward to provision and configure…they’re also easy to program against, from just about any programming environment, in a RESTful manner.  And for more .NET-centric implementations, Azure AppFabric caching takes the technology formerly known as “Velocity” and throws it up into the cloud, speeding data access even more. Snapping in Place Once you get the hang of it, this stuff just starts to work in a way that becomes natural to understand.  I wasn’t expecting that, and I was really happy to discover it. In retrospect, I am not surprised, because I think the various Azure teams are the center of gravity for Redmond’s innovation right now.  The products belie this and so do my observations of the product teams’ motivation and high morale.  It is really good to see this; Microsoft needs to lead somewhere, and they need to be seen as the underdog while doing so.  With Azure, both requirements are in place.   BPOS: Bad Acronym, Easy Setup BPOS is about products you already know; Exchange, SharePoint, Live Meeting and Office Communications Server.  As such, it’s hard not to be underwhelmed by BPOS.  Until you realize how easy it makes it to get all that stuff set up.  I would say that from sign-up to productive use took me about 45 minutes…and that included the time necessary to wrestle with my DNS provider, set up Outlook and my SmartPhone up to talk to the Exchange account, create my SharePoint site collection, and configure the Outlook Conferencing add-in to talk to the provisioned Live Meeting account. Never before did I think setting up my own Exchange mail could come anywhere close to the simplicity of setting up an SMTP/POP account, and yet BPOS actually made it faster.   What I want from my Azure Christmas Next Year Not everything about Microsoft’s cloud is good.  I close this post with a list of things I’d like to see addressed: BPOS offerings are still based on the 2007 Wave of Microsoft server technologies.  We need to get to 2010, and fast.  Arguably, the 2010 products should have been released to the off-premises channel before the on-premise sone.  Office 365 can’t come fast enough. Azure’s Internet tooling and domain naming, is scattered and confusing.  Deployed ASP.NET applications go to cloudapp.net; SQL Azure and Azure storage work off windows.net.  The Azure portal and Project Houston are at azure.com.  Then there’s appfabriclabs.com and sqlazurelabs.com.  There is a new Silverlight portal that replaces most, but not all of the HTML ones.  And Project Houston is Silvelright-based too, though separate from the Silverlight portal tooling. Microsoft is the king off tooling.  They should not make me keep an entire OneNote notebook full of portal links, account names, access keys, assemblies and namespaces and do so much CTRL-C/CTRL-V work.  I’d like to see more project templates, have them automatically reference the appropriate assemblies, generate the right using/Imports statements and prime my config files with the right markup.  Then I want a UI that lets me log in with my Live ID and pick the appropriate project, database, namespace and key string to get set up fast. Beta programs, if they’re open, should onboard me quickly.  I know the process is difficult and everyone’s going as fast as they can.  But I don’t know why it’s so difficult or why it takes so long.  Getting developers up to speed on new features quickly helps popularize the platform.  Make this a priority. Make Azure accessible from the simplicity platforms, i.e. ASP.NET Web Pages (Razor) and LightSwitch.  Support .NET 4 now.  Make WebMatrix, IIS Express and SQL Compact work with the Azure development fabric. Have HTML helpers make Azure programming easier.  Have LightSwitch work with SQL Azure and not require SQL Express.  LightSwitch has some promising Azure integration now.  But we need more.  WebMatrix has none and that’s just silly, now that the Extra Small Instance is being introduced. The Windows Azure Platform Training Kit is great.  But I want Microsoft to make it even better and I want them to evangelize it much more aggressively.  There’s a lot of good material on Azure development out there, but it’s scattered in the same way that the platform is.   The Training Kit ties a lot of disparate stuff together nicely.  Make it known. Should Old Acquaintance Be Forgot All in all, diving deep into Azure was a good way to end the year.  Diving deeper into Azure should a great way to spend next year, not just for me, but for Microsoft too.

    Read the article

  • NUMA-aware placement of communication variables

    - by Dave
    For classic NUMA-aware programming I'm typically most concerned about simple cold, capacity and compulsory misses and whether we can satisfy the miss by locally connected memory or whether we have to pull the line from its home node over the coherent interconnect -- we'd like to minimize channel contention and conserve interconnect bandwidth. That is, for this style of programming we're quite aware of where memory is homed relative to the threads that will be accessing it. Ideally, a page is collocated on the node with the thread that's expected to most frequently access the page, as simple misses on the page can be satisfied without resorting to transferring the line over the interconnect. The default "first touch" NUMA page placement policy tends to work reasonable well in this regard. When a virtual page is first accessed, the operating system will attempt to provision and map that virtual page to a physical page allocated from the node where the accessing thread is running. It's worth noting that the node-level memory interleaving granularity is usually a multiple of the page size, so we can say that a given page P resides on some node N. That is, the memory underlying a page resides on just one node. But when thinking about accesses to heavily-written communication variables we normally consider what caches the lines underlying such variables might be resident in, and in what states. We want to minimize coherence misses and cache probe activity and interconnect traffic in general. I don't usually give much thought to the location of the home NUMA node underlying such highly shared variables. On a SPARC T5440, for instance, which consists of 4 T2+ processors connected by a central coherence hub, the home node and placement of heavily accessed communication variables has very little impact on performance. The variables are frequently accessed so likely in M-state in some cache, and the location of the home node is of little consequence because a requester can use cache-to-cache transfers to get the line. Or at least that's what I thought. Recently, though, I was exploring a simple shared memory point-to-point communication model where a client writes a request into a request mailbox and then busy-waits on a response variable. It's a simple example of delegation based on message passing. The server polls the request mailbox, and having fetched a new request value, performs some operation and then writes a reply value into the response variable. As noted above, on a T5440 performance is insensitive to the placement of the communication variables -- the request and response mailbox words. But on a Sun/Oracle X4800 I noticed that was not the case and that NUMA placement of the communication variables was actually quite important. For background an X4800 system consists of 8 Intel X7560 Xeons . Each package (socket) has 8 cores with 2 contexts per core, so the system is 8x8x2. Each package is also a NUMA node and has locally attached memory. Every package has 3 point-to-point QPI links for cache coherence, and the system is configured with a twisted ladder "mobius" topology. The cache coherence fabric is glueless -- there's not central arbiter or coherence hub. The maximum distance between any two nodes is just 2 hops over the QPI links. For any given node, 3 other nodes are 1 hop distant and the remaining 4 nodes are 2 hops distant. Using a single request (client) thread and a single response (server) thread, a benchmark harness explored all permutations of NUMA placement for the two threads and the two communication variables, measuring the average round-trip-time and throughput rate between the client and server. In this benchmark the server simply acts as a simple transponder, writing the request value plus 1 back into the reply field, so there's no particular computation phase and we're only measuring communication overheads. In addition to varying the placement of communication variables over pairs of nodes, we also explored variations where both variables were placed on one page (and thus on one node) -- either on the same cache line or different cache lines -- while varying the node where the variables reside along with the placement of the threads. The key observation was that if the client and server threads were on different nodes, then the best placement of variables was to have the request variable (written by the client and read by the server) reside on the same node as the client thread, and to place the response variable (written by the server and read by the client) on the same node as the server. That is, if you have a variable that's to be written by one thread and read by another, it should be homed with the writer thread. For our simple client-server model that means using split request and response communication variables with unidirectional message flow on a given page. This can yield up to twice the throughput of less favorable placement strategies. Our X4800 uses the QPI 1.0 protocol with source-based snooping. Briefly, when node A needs to probe a cache line it fires off snoop requests to all the nodes in the system. Those recipients then forward their response not to the original requester, but to the home node H of the cache line. H waits for and collects the responses, adjudicates and resolves conflicts and ensures memory-model ordering, and then sends a definitive reply back to the original requester A. If some node B needed to transfer the line to A, it will do so by cache-to-cache transfer and let H know about the disposition of the cache line. A needs to wait for the authoritative response from H. So if a thread on node A wants to write a value to be read by a thread on node B, the latency is dependent on the distances between A, B, and H. We observe the best performance when the written-to variable is co-homed with the writer A. That is, we want H and A to be the same node, as the writer doesn't need the home to respond over the QPI link, as the writer and the home reside on the very same node. With architecturally informed placement of communication variables we eliminate at least one QPI hop from the critical path. Newer Intel processors use the QPI 1.1 coherence protocol with home-based snooping. As noted above, under source-snooping a requester broadcasts snoop requests to all nodes. Those nodes send their response to the home node of the location, which provides memory ordering, reconciles conflicts, etc., and then posts a definitive reply to the requester. In home-based snooping the snoop probe goes directly to the home node and are not broadcast. The home node can consult snoop filters -- if present -- and send out requests to retrieve the line if necessary. The 3rd party owner of the line, if any, can respond either to the home or the original requester (or even to both) according to the protocol policies. There are myriad variations that have been implemented, and unfortunately vendor terminology doesn't always agree between vendors or with the academic taxonomy papers. The key is that home-snooping enables the use of a snoop filter to reduce interconnect traffic. And while home-snooping might have a longer critical path (latency) than source-based snooping, it also may require fewer messages and less overall bandwidth. It'll be interesting to reprise these experiments on a platform with home-based snooping. While collecting data I also noticed that there are placement concerns even in the seemingly trivial case when both threads and both variables reside on a single node. Internally, the cores on each X7560 package are connected by an internal ring. (Actually there are multiple contra-rotating rings). And the last-level on-chip cache (LLC) is partitioned in banks or slices, which with each slice being associated with a core on the ring topology. A hardware hash function associates each physical address with a specific home bank. Thus we face distance and topology concerns even for intra-package communications, although the latencies are not nearly the magnitude we see inter-package. I've not seen such communication distance artifacts on the T2+, where the cache banks are connected to the cores via a high-speed crossbar instead of a ring -- communication latencies seem more regular.

    Read the article

  • Corsair Hackers Reboot

    It wasn't easy for me to attend but it was absolutely worth to go. The Linux User Group of Mauritius (LUGM) organised another get-together for any open source enthusiast here on the island. Strangely named "Corsair Hackers Reboot" but it stands for a positive cause: "Corsair Hackers Reboot Event A collaborative activity involving LUGM, UoM Computer Club, Fortune Way Shopping Mall and several geeks from around the island, striving to put FOSS into homes & offices. The public is invited to discover and explore Free Software & Open Source." And it was a good opportunity for me and the kids to visit the east coast of Mauritius, too. Perfect timing It couldn't have been better... Why? Well, for two important reasons (in terms of IT): End of support for Microsoft Windows XP - 08.04.2014 Release of Ubuntu 14.04 Long Term Support - 17.04.2014 Quite funnily, those two IT dates weren't the initial reasons and only during the weeks of preparations we put those together. And therefore it was even more positive to promote the use of Linux and open source software in general to a broader audience. Getting there ... Thanks to the new motor way M3 and all the additional road work which has been completed recently it was very simple to get across the island in a very quick and relaxed manner. Compared to my trips in the early days of living in Mauritius (and riding on a scooter) it was very smooth and within less than an hour we hit Centrale de Flacq. Well, being in the city doesn't necessarily mean that one has arrived at the destination. But thanks to modern technology I had a quick look on Google Maps, and we finally managed to get a parking behind the huge bus terminal in Flacq. From there it was just a short walk to Fortune Way. The children were trying to count the number of buses... Well, lots and lots of buses - really impressive actually. What was presented? There were different areas set up. Right at the entrance one's attention was directly drawn towards the elevated hacker's stage. Similar to rock stars performing their gig there was bunch of computers, laptops and networking equipment in order to cater the right working conditions for coding/programming challenge(s) on the one hand and for the pen-testing or system hacking competition on the other hand. Personally, I was very impresses that actually Nitin took care of the pen-testing competition. He hardly started one year back with Linux in general, and Kali Linux specifically. Seeing his personal development from absolute newbie to a decent Linux system administrator within such a short period of time, is really impressive. His passion to open source software made him a living. Next, clock-wise seen, was the Kid's Corner with face-painting as the main attraction. Additionally, there were numerous paper print outs to colour. Plus a decent workstation with the educational suite GCompris. Of course, my little ones were into that. They already know GCompris since a while as they are allowed to use it on an IGEL thin client terminal here at home. To simplify my life, I set up GCompris as full-screen guest session on the server, and they can pass the login screen without any further obstacles. And because it's a thin client hooked up to a XDMCP remote session I don't have to worry about the hardware on their desk, too. The next section was the main attraction of the event: BYOD - Bring Your Own Device Well, compared to the usual context of BYOD the corsairs had a completely different intention. Here, you could bring your own laptop and a team of knowledgeable experts - read: geeks and so on - offered to fully convert your system on any Linux distribution of your choice. And even though I came later, I was told that the USB pen drives had been in permanent use. From being prepared via dd command over launching LiveCD session to finally installing a fresh Linux system on bare metal. Most interestingly, I did a similar job already a couple of months ago, while upgrading an existing Windows XP system to Xubuntu 13.10. So far, the female owner is very happy and enjoys her system almost every evening to go shopping online, checking mails, and reading latest news from the Anime world. Back to the Hackers event, Ish told me that they managed approximately 20 conversion during the day. Furthermore, Ajay and others gladly assisted some visitors with some tricky issues and by the end of the day you can call is a success. While I was around, there was a elderly male visitor that got a full-fledged system conversion to a Linux system running completely in French language. A little bit more to the centre it was Yasir's turn to demonstrate his Arduino hardware that he hooked up with an experimental electrical circuit board connected to an LCD matrix display. That's the real spirit of hacking, and he showed some minor adjustments on the fly while demo'ing the system. Also, very interesting there was a thermal sensor around. Personally, I think that platforms like the Arduino as well as the Raspberry Pi have a great potential at a very affordable price in order to bring a better understanding of electronics as well as computer programming to a broader audience. It would be great to see more of those experiments during future activities. And last but not least there were a small number of vendors. Amongst them was Emtel - once again as sponsor of the general internet connectivity - and another hardware supplier from Riche Terre shopping mall. They had a good collection of Android related gimmicks, like a autonomous web cam that can convert any TV with HDMI connector into an online video chat system given WiFi. It's actually kind of awesome to have a Skype or Google hangout video session on the big screen rather than on the laptop. Some pictures of the event LUGM: Great conversations on Linux, open source and free software during the Corsair Hackers Reboot LUGM: Educational workstation running GCompris suite attracted the youngest attendees of the day. Of course, face painting had to be done prior to hacking... LUGM: Nadim demoing some Linux specifics to interested visitors. Everyone was pretty busy during the whole day LUGM: The hacking competition, here pen-testing a wireless connection and access point between multiple machines LUGM: Well prepared workstations to be able to 'upgrade' visitors' machines to any Linux operating system Final thoughts Gratefully, during the preparations of the event I was invited to leave some comments or suggestions, and the team of the LUGM did a great job. The outdoor banner was a eye-catcher, the various flyers and posters for the event were clearly written and as far as I understood from the quick chats I had with Ish, Nadim, Nitin, Ajay, and of course others all were very happy about the event execution. Great job, LUGM! And I'm already looking forward to the next Corsair Hackers Reboot event ... Crossing fingers: Very soon and hopefully this year again :) Update: In the media The event had been announced in local media, too. L'Express: Salon informatique: Hacking Challenge à Flacq

    Read the article

  • PostSharp, Obfuscation, and IL

    - by Simon Cooper
    Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day!

    Read the article

  • PostSharp, Obfuscation, and IL

    - by simonc
    Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day! Cross posted from Simple Talk.

    Read the article

  • Super constructor must be a first statement in Java constructor [closed]

    - by Val
    I know the answer: "we need rules to prevent shooting into your own foot". Ok, I make millions of programming mistakes every day. To be prevented, we need one simple rule: prohibit all JLS and do not use Java. If we explain everything by "not shooting your foot", this is reasonable. But there is not much reason is such reason. When I programmed in Delphy, I always wanted the compiler to check me if I read uninitializable. I have discovered myself that is is stupid to read uncertain variable because it leads unpredictable result and is errorenous obviously. By just looking at the code I could see if there is an error. I wished if compiler could do this job. It is also a reliable signal of programming error if function does not return any value. But I never wanted it do enforce me the super constructor first. Why? You say that constructors just initialize fields. Super fields are derived; extra fields are introduced. From the goal point of view, it does not matter in which order you initialize the variables. I have studied parallel architectures and can say that all the fields can even be assigned in parallel... What? Do you want to use the unitialized fields? Stupid people always want to take away our freedoms and break the JLS rules the God gives to us! Please, policeman, take away that person! Where do I say so? I'm just saying only about initializing/assigning, not using the fields. Java compiler already defends me from the mistake of accessing notinitialized. Some cases sneak but this example shows how this stupid rule does not save us from the read-accessing incompletely initialized in construction: public class BadSuper { String field; public String toString() { return "field = " + field; } public BadSuper(String val) { field = val; // yea, superfirst does not protect from accessing // inconstructed subclass fields. Subclass constr // must be called before super()! System.err.println(this); } } public class BadPost extends BadSuper { Object o; public BadPost(Object o) { super("str"); this. o = o; } public String toString() { // superconstructor will boom here, because o is not initialized! return super.toString() + ", obj = " + o.toString(); } public static void main(String[] args) { new BadSuper("test 1"); new BadPost(new Object()); } } It shows that actually, subfields have to be inilialized before the supreclass! Meantime, java requirement "saves" us from writing specializing the class by specializing what the super constructor argument is, public class MyKryo extends Kryo { class MyClassResolver extends DefaultClassResolver { public Registration register(Registration registration) { System.out.println(MyKryo.this.getDepth()); return super.register(registration); } } MyKryo() { // cannot instantiate MyClassResolver in super super(new MyClassResolver(), new MapReferenceResolver()); } } Try to make it compilable. It is always pain. Especially, when you cannot assign the argument later. Initialization order is not important for initialization in general. I could understand that you should not use super methods before initializing super. But, the requirement for super to be the first statement is different. It only saves you from the code that does useful things simply. I do not see how this adds safety. Actually, safety is degraded because we need to use ugly workarounds. Doing post-initialization, outside the constructors also degrades safety (otherwise, why do we need constructors?) and defeats the java final safety reenforcer. To conclude Reading not initialized is a bug. Initialization order is not important from the computer science point of view. Doing initalization or computations in different order is not a bug. Reenforcing read-access to not initialized is good but compilers fail to detect all such bugs Making super the first does not solve the problem as it "Prevents" shooting into right things but not into the foot It requires to invent workarounds, where, because of complexity of analysis, it is easier to shoot into the foot doing post-initialization outside the constructors degrades safety (otherwise, why do we need constructors?) and that degrade safety by defeating final access modifier When there was java forum alive, java bigots attecked me for these thoughts. Particularly, they dislaked that fields can be initialized in parallel, saying that natural development ensures correctness. When I replied that you could use an advanced engineering to create a human right away, without "developing" any ape first, and it still be an ape, they stopped to listen me. Cos modern technology cannot afford it. Ok, Take something simpler. How do you produce a Renault? Should you construct an Automobile first? No, you start by producing a Renault and, once completed, you'll see that this is an automobile. So, the requirement to produce fields in "natural order" is unnatural. In case of alarmclock or armchair, which are still chair and clock, you may need first develop the base (clock and chair) and then add extra. So, I can have examples where superfields must be initialized first and, oppositely, when they need to be initialized later. The order does not exist in advance. So, the compiler cannot be aware of the proper order. Only programmer/constructor knows is. Compiler should not take more responsibility and enforce the wrong order onto programmer. Saying that I cannot initialize some fields because I did not ininialized the others is like "you cannot initialize the thing because it is not initialized". This is a kind of argument we have. So, to conclude once more, the feature that "protects" me from doing things in simple and right way in order to enforce something that does not add noticeably to the bug elimination at that is a strongly negative thing and it pisses me off, altogether with the all the arguments to support it I've seen so far. It is "a conceptual question about software development" Should there be the requirement to call super() first or not. I do not know. If you do or have an idea, you have place to answer. I think that I have provided enough arguments against this feature. Lets appreciate the ones who benefit form it. Let it just be something more than simple abstract and stupid "write your own language" or "protection" kind of argument. Why do we need it in the language that I am going to develop?

    Read the article

  • Error in installing ZTE AC2738 on ubuntu 3.0.0-12-generic

    - by Netro
    I am getting this error ,struct usb_serial_driver has no member named shutdown. I am installing on 64bit ubuntu 3.0.0-12-generic ... Beginning Verify CD ... ... Verify CD Succeed! ... Beginning Copy Install Package Files ... ... will take a long time, waiting 5 seconds, please ... Copy Install Package Files Succeed! ... 'ztemtApp' previous version not found. and install now Beginning install ... ... Current linux release version is 'Ubuntu' ... Checking 'App' process ... Checking old installation ... Installing ... Current Path is : . : /tmp/ztemt_datacard/Linux 1. Checking Previous Version ... 2. Copying Data Bin ... ... will take a few seconds, please waiting ... /tmp/ztemt_datacard/Linux 3. Auto Load Usb Driver Module ... Rather than invoking init scripts through /etc/init.d, use the service(8) utility, e.g. service acpid restart Since the script you are attempting to invoke has been converted to an Upstart job, you may also use the stop(8) and then start(8) utilities, e.g. stop acpid ; start acpid. The restart(8) utility is also available. acpid stop/waiting acpid start/running, process 11802 4. Changing pppd Options ... 5. Changing File Permission ... 6. Deleting Qt lib When Local QT Vertion > V4.4.0 ... ... Package 'libqtgui4' exist ... QT_VERSION = 4 7. Deleting process id file: EVDOApp.pid ... 8. Making USB Serial Driver Module : ztemt.ko ... ... will take a few seconds, please waiting ... make -C /lib/modules/3.0.0-12-generic/build M=/usr/local/bin/ztemtApp/zteusbserial/below2.6.27 modules make[1]: Entering directory `/usr/src/linux-headers-3.0.0-12-generic' CC [M] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.o /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘destroy_serial’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:159:14: error: ‘struct usb_serial_driver’ has no member named ‘shutdown’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:165:18: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_open’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:241:36: error: ‘struct usb_serial_port’ has no member named ‘mutex’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:246:8: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:251:6: error: ‘struct usb_serial_port’ has no member named ‘tty’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:253:10: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:265:3: warning: passing argument 1 of ‘serial->type->open’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:265:3: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:265:3: warning: passing argument 2 of ‘serial->type->open’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:265:3: note: expected ‘struct usb_serial_port *’ but argument is of type ‘struct file *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:270:20: error: ‘struct usb_serial_port’ has no member named ‘mutex’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:276:6: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:278:6: error: ‘struct usb_serial_port’ has no member named ‘tty’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:279:20: error: ‘struct usb_serial_port’ has no member named ‘mutex’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_close’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:355:18: error: ‘struct usb_serial_port’ has no member named ‘mutex’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:357:10: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:358:21: error: ‘struct usb_serial_port’ has no member named ‘mutex’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:371:8: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:372:10: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:375:3: error: too many arguments to function ‘port->serial->type->close’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:377:11: error: ‘struct usb_serial_port’ has no member named ‘tty’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:378:12: error: ‘struct usb_serial_port’ has no member named ‘tty’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:379:9: error: ‘struct usb_serial_port’ has no member named ‘tty’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:380:8: error: ‘struct usb_serial_port’ has no member named ‘tty’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:386:20: error: ‘struct usb_serial_port’ has no member named ‘mutex’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_write’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:407:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:413:2: warning: passing argument 1 of ‘port->serial->type->write’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:413:2: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:413:2: warning: passing argument 2 of ‘port->serial->type->write’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:413:2: note: expected ‘struct usb_serial_port *’ but argument is of type ‘const unsigned char *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:413:2: warning: passing argument 3 of ‘port->serial->type->write’ makes pointer from integer without a cast [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:413:2: note: expected ‘const unsigned char *’ but argument is of type ‘int’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:413:2: error: too few arguments to function ‘port->serial->type->write’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_write_room’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:429:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:435:2: warning: passing argument 1 of ‘port->serial->type->write_room’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:435:2: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_chars_in_buffer’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:451:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:457:2: warning: passing argument 1 of ‘port->serial->type->chars_in_buffer’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:457:2: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_throttle’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:472:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:479:3: warning: passing argument 1 of ‘port->serial->type->throttle’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:479:3: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_unthrottle’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:491:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:498:3: warning: passing argument 1 of ‘port->serial->type->unthrottle’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:498:3: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_ioctl’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:511:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:518:3: warning: passing argument 1 of ‘port->serial->type->ioctl’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:518:3: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:518:3: warning: passing argument 2 of ‘port->serial->type->ioctl’ makes integer from pointer without a cast [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:518:3: note: expected ‘unsigned int’ but argument is of type ‘struct file *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:518:3: error: too many arguments to function ‘port->serial->type->ioctl’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_set_termios’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:535:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:542:3: warning: passing argument 1 of ‘port->serial->type->set_termios’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:542:3: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:542:3: warning: passing argument 2 of ‘port->serial->type->set_termios’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:542:3: note: expected ‘struct usb_serial_port *’ but argument is of type ‘struct termios *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:542:3: error: too few arguments to function ‘port->serial->type->set_termios’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_break’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:554:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:561:3: warning: passing argument 1 of ‘port->serial->type->break_ctl’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:561:3: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_tiocmget’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:629:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:635:3: warning: passing argument 1 of ‘port->serial->type->tiocmget’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:635:3: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:635:3: error: too many arguments to function ‘port->serial->type->tiocmget’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘serial_tiocmset’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:651:11: error: ‘struct usb_serial_port’ has no member named ‘open_count’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:657:3: warning: passing argument 1 of ‘port->serial->type->tiocmset’ from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:657:3: note: expected ‘struct tty_struct *’ but argument is of type ‘struct usb_serial_port *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:657:3: warning: passing argument 2 of ‘port->serial->type->tiocmset’ makes integer from pointer without a cast [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:657:3: note: expected ‘unsigned int’ but argument is of type ‘struct file *’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:657:3: error: too many arguments to function ‘port->serial->type->tiocmset’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘usb_serial_port_work’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:697:12: error: ‘struct usb_serial_port’ has no member named ‘tty’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘port_release’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:709:2: error: ‘struct device’ has no member named ‘bus_id’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘usb_serial_probe’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:858:2: error: implicit declaration of function ‘lock_kernel’ [-Werror=implicit-function-declaration] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:861:3: error: implicit declaration of function ‘unlock_kernel’ [-Werror=implicit-function-declaration] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1034:3: error: ‘struct usb_serial_port’ has no member named ‘mutex’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1182:23: error: ‘struct device’ has no member named ‘bus_id’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1182:51: error: ‘struct device’ has no member named ‘bus_id’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1183:3: error: ‘struct device’ has no member named ‘bus_id’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘usb_serial_disconnect’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1257:13: error: ‘struct usb_serial_port’ has no member named ‘tty’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1258:21: error: ‘struct usb_serial_port’ has no member named ‘tty’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: At top level: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1280:2: warning: initialization from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1280:2: warning: (near initialization for ‘serial_ops.ioctl’) [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1281:2: warning: initialization from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1281:2: warning: (near initialization for ‘serial_ops.set_termios’) [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1284:2: warning: initialization from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1284:2: warning: (near initialization for ‘serial_ops.break_ctl’) [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1286:2: error: unknown field ‘read_proc’ specified in initializer /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1286:2: warning: initialization from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1286:2: warning: (near initialization for ‘serial_ops.ioctl’) [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1287:2: warning: initialization from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1287:2: warning: (near initialization for ‘serial_ops.tiocmget’) [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1288:2: warning: initialization from incompatible pointer type [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1288:2: warning: (near initialization for ‘serial_ops.tiocmset’) [enabled by default] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘usb_serial_init’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1352:2: error: implicit declaration of function ‘info’ [-Werror=implicit-function-declaration] /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c: In function ‘fixup_generic’: /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1406:2: error: ‘struct usb_serial_driver’ has no member named ‘shutdown’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1406:2: error: ‘struct usb_serial_driver’ has no member named ‘shutdown’ /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1406:1: error: ‘usb_serial_generic_shutdown’ undeclared (first use in this function) /usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.c:1406:1: note: each undeclared identifier is reported only once for each function it appears in cc1: some warnings being treated as errors make[2]: *** [/usr/local/bin/ztemtApp/zteusbserial/below2.6.27/usb-serial.o] Error 1 make[1]: *** [_module_/usr/local/bin/ztemtApp/zteusbserial/below2.6.27] Error 2 make[1]: Leaving directory `/usr/src/linux-headers-3.0.0-12-generic' make: *** [modules] Error 2 Install finished! Any suggestion? Update: from installation document , In some special cases, the setup package can’t automatically compile the driver, so you need change the configurations yourself and manually compile the driver. Method: enter the directory: /usr/local/bin/ztemtApp/zteusbserial, and find the corresponding kernel version of current system. I can see 2.6.27 2.6.28 2.6.29 2.6.30 2.6.31 2.6.32 2.6.33 2.6.34 2.6.35 2.6.36 2.6.37 2.6.38 2.6.39 below2.6.2 in the directory. Which version shall I pick up for installation? Readme file says, we have to do this to insert ztemt.ko in kernel.

    Read the article

  • Can't make AWUS036H work in Ubuntu 12.10

    - by sfrj
    I am using 64 bit Ubuntu 12.10. This is my kernel version: Linux 3.5.0-19-generic #30-Ubuntu SMP Tue Nov 13 17:48:01 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux My wireless card is an AWUSU36H The first thing I do to install the driver is copy the driver from the CD to the Downloads folder. cd /media/me/AWUS036H/Drivers/RTL8187L/Unix (Linux)/Linux driver for kernel 2.6.X$ cp rtl8187_linux_26.1025.0328.2007.tar.gz ~/Downloads/ Then I extract the tar tar xvfz rtl8187_linux_26.1025.0328.2007.tar.gz I navigate into the extracted folder, and I try to follow the instructions in the Readme.txt cd rtl8187_linux_26.1025.0328.2007 This are the contents of the folder: drv.tar.gz makedrv stack.tar.gz wlan0rmv ieee80211 ReadMe.txt wlan0dhcp wlan0up ifcfg-wlan0 rtl8187 wlan0down wpa_supplicant-0.4.9 This is what the Readme.txt says: Release Date: 2006-02-09, ver 1.2^M RTL8187 Linux driver version 1.2^M ^M --This driver supports RealTek RTL8187 Wireless LAN driver for ^M Fedora Core 2/3/4/5, Debian 3.1, Mandrake 10.2/Mandriva 2006, ^M SUSE 9.3/10.1/10.2, Gentoo 3.1, etc.^M - Support Client mode for either infrastructure or adhoc mode^M - Support WEP and WPAPSK connection^M ^M < Component >^M The driver is composed of several parts:^M 1. Module source code^M stack.tar.gz^M drv.tar.gz^M ^M 2. Script ot build the modules^M makedrv^M ^M 3. Script to load/unload modules^M wlan0up^M wlan0down ^M ^M 4. Script and configuration for DHCP^M "ReadMe.txt" [readonly] 140 lines, 4590 characters So what I do know is extract both of the compressed files: sudo tar xvfz drv.tar.gz sudo tar xvfz stack.tar.gz This 2 commands will add some data to the folders ieee80211 and rtl8187 At this point I get lost, and I don't know what to do. If I go in each of this 2 folders and I run the sudo make command then I get errors like this one: sudo makemake -C /lib/modules/3.5.0-19-generic/build M=/home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187 modules make[1]: Entering directory `/usr/src/linux-headers-3.5.0-19-generic' CC [M] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187/r8187_core.o In file included from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187/r8187_core.c:64:0: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187/r8187.h:29:26: fatal error: linux/config.h: No such file or directory compilation terminated. make[2]: *** [/home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187/r8187_core.o] Error 1 make[1]: *** [_module_/home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187] Error 2 make[1]: Leaving directory `/usr/src/linux-headers-3.5.0-19-generic' make: *** [modules] Error 2 If I try to run any of the script ./makedrv that the instructions describe, then I also get an error: ~/Downloads/rtl8187_linux_26.1025.0328.2007$ sudo ./makedrv [sudo] password for me: ieee80211/ ieee80211/license ieee80211/ieee80211_crypt.c ieee80211/ieee80211_tx.c ieee80211/ieee80211_softmac.c ieee80211/ieee80211_softmac_wx.c ieee80211/ieee80211_module.c ieee80211/ieee80211_crypt_ccmp.c ieee80211/ieee80211_rx.c ieee80211/tags ieee80211/ieee80211_crypt_tkip.c ieee80211/Makefile ieee80211/readme ieee80211/.tmp_versions/ ieee80211/.tmp_versions/ieee80211-rtl.mod ieee80211/.tmp_versions/ieee80211_crypt_wep-rtl.mod ieee80211/.tmp_versions/ieee80211_crypt_tkip-rtl.mod ieee80211/.tmp_versions/ieee80211_crypt-rtl.mod ieee80211/.tmp_versions/ieee80211_crypt_ccmp-rtl.mod ieee80211/ieee80211_crypt_wep.c ieee80211/ieee80211.h ieee80211/ieee80211_wx.c ieee80211/ieee80211_crypt.h rtl8187/ rtl8187/license rtl8187/r8180_rtl8225z2.c rtl8187/r8180_rtl8225.h rtl8187/r8187_led.c rtl8187/r8180_93cx6.h rtl8187/r8180_wx.h rtl8187/r8180_hw.h rtl8187/copying rtl8187/r8187_led.h rtl8187/r8180_pm.h rtl8187/tags rtl8187/r8187.h rtl8187/Makefile rtl8187/r8180_rtl8225.c rtl8187/readme rtl8187/install rtl8187/.tmp_versions/ rtl8187/.tmp_versions/r8187.mod rtl8187/changes rtl8187/r8180_wx.c rtl8187/r8180_pm.c rtl8187/r8187_core.c rtl8187/r8180_93cx6.c rtl8187/authors rtl8187/ieee80211.h rtl8187/ieee80211_crypt.h rm -f *.mod.c *.mod *.o .*.cmd *.ko *~ rm -rf /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/tmp make -C /lib/modules/3.5.0-19-generic/build M=/home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211 modules make[1]: Entering directory `/usr/src/linux-headers-3.5.0-19-generic' CC [M] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.o In file included from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:17:0: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211.h:1019:24: error: field ‘ps_task’ has incomplete type /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c: In function ‘ieee80211_softmac_scan_wq’: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:421:2: warning: passing argument 2 of ‘queue_delayed_work’ from incompatible pointer type [enabled by default] In file included from include/linux/srcu.h:32:0, from include/linux/notifier.h:15, from /usr/src/linux-headers-3.5.0-19-generic/arch/x86/include/asm/uprobes.h:26, from include/linux/uprobes.h:35, from include/linux/mm_types.h:15, from include/linux/kmemcheck.h:4, from include/linux/skbuff.h:18, from include/linux/if_ether.h:134, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211.h:26, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:17: include/linux/workqueue.h:371:12: note: expected ‘struct delayed_work *’ but argument is of type ‘struct work_struct *’ /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c: In function ‘ieee80211_softmac_stop_scan’: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:495:3: warning: passing argument 1 of ‘cancel_delayed_work’ from incompatible pointer type [enabled by default] In file included from include/linux/srcu.h:32:0, from include/linux/notifier.h:15, from /usr/src/linux-headers-3.5.0-19-generic/arch/x86/include/asm/uprobes.h:26, from include/linux/uprobes.h:35, from include/linux/mm_types.h:15, from include/linux/kmemcheck.h:4, from include/linux/skbuff.h:18, from include/linux/if_ether.h:134, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211.h:26, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:17: include/linux/workqueue.h:410:20: note: expected ‘struct delayed_work *’ but argument is of type ‘struct work_struct *’ /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c: In function ‘ieee80211_associate_abort’: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:915:2: warning: passing argument 2 of ‘queue_delayed_work’ from incompatible pointer type [enabled by default] In file included from include/linux/srcu.h:32:0, from include/linux/notifier.h:15, from /usr/src/linux-headers-3.5.0-19-generic/arch/x86/include/asm/uprobes.h:26, from include/linux/uprobes.h:35, from include/linux/mm_types.h:15, from include/linux/kmemcheck.h:4, from include/linux/skbuff.h:18, from include/linux/if_ether.h:134, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211.h:26, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:17: include/linux/workqueue.h:371:12: note: expected ‘struct delayed_work *’ but argument is of type ‘struct work_struct *’ /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c: In function ‘ieee80211_rx_frame_softmac’: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:1527:3: error: implicit declaration of function ‘tasklet_schedule’ [-Werror=implicit-function-declaration] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c: In function ‘ieee80211_stop_protocol_rtl’: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2120:2: warning: passing argument 1 of ‘cancel_delayed_work’ from incompatible pointer type [enabled by default] In file included from include/linux/srcu.h:32:0, from include/linux/notifier.h:15, from /usr/src/linux-headers-3.5.0-19-generic/arch/x86/include/asm/uprobes.h:26, from include/linux/uprobes.h:35, from include/linux/mm_types.h:15, from include/linux/kmemcheck.h:4, from include/linux/skbuff.h:18, from include/linux/if_ether.h:134, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211.h:26, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:17: include/linux/workqueue.h:410:20: note: expected ‘struct delayed_work *’ but argument is of type ‘struct work_struct *’ /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c: In function ‘ieee80211_softmac_init’: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2229:78: error: macro "INIT_WORK" passed 3 arguments, but takes just 2 /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2229:2: error: ‘INIT_WORK’ undeclared (first use in this function) /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2229:2: note: each undeclared identifier is reported only once for each function it appears in /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2230:88: error: macro "INIT_WORK" passed 3 arguments, but takes just 2 /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2231:94: error: macro "INIT_WORK" passed 3 arguments, but takes just 2 /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2232:96: error: macro "INIT_WORK" passed 3 arguments, but takes just 2 /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2233:82: error: macro "INIT_WORK" passed 3 arguments, but takes just 2 /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2234:82: error: macro "INIT_WORK" passed 3 arguments, but takes just 2 /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2244:2: error: implicit declaration of function ‘tasklet_init’ [-Werror=implicit-function-declaration] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c: In function ‘ieee80211_softmac_free’: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2255:2: warning: passing argument 1 of ‘cancel_delayed_work’ from incompatible pointer type [enabled by default] In file included from include/linux/srcu.h:32:0, from include/linux/notifier.h:15, from /usr/src/linux-headers-3.5.0-19-generic/arch/x86/include/asm/uprobes.h:26, from include/linux/uprobes.h:35, from include/linux/mm_types.h:15, from include/linux/kmemcheck.h:4, from include/linux/skbuff.h:18, from include/linux/if_ether.h:134, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211.h:26, from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:17: include/linux/workqueue.h:410:20: note: expected ‘struct delayed_work *’ but argument is of type ‘struct work_struct *’ /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c: In function ‘ieee80211_wpa_set_encryption’: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2489:3: error: implicit declaration of function ‘request_module’ [-Werror=implicit-function-declaration] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2518:3: error: implicit declaration of function ‘try_module_get’ [-Werror=implicit-function-declaration] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c: At top level: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2663:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2663:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2663:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2664:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2664:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2664:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2665:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2665:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2665:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2666:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2666:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2666:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2667:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2667:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2667:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2668:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2668:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2668:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2669:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2669:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2669:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2670:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2670:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2670:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2671:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2671:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2671:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2672:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2672:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2672:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2673:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2673:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2673:1: warning: parameter names (without types) in function declaration [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2674:1: warning: data definition has no type or storage class [enabled by default] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2674:1: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’ [-Wimplicit-int] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:2674:1: warning: parameter names (without types) in function declaration [enabled by default] In file included from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.c:17:0: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211.h:1212:37: warning: ‘netdev_priv’ is static but used in inline function ‘ieee80211_priv’ which is not static [enabled by default] cc1: some warnings being treated as errors make[2]: *** [/home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211/ieee80211_softmac.o] Error 1 make[1]: *** [_module_/home/me/Downloads/rtl8187_linux_26.1025.0328.2007/ieee80211] Error 2 make[1]: Leaving directory `/usr/src/linux-headers-3.5.0-19-generic' make: *** [modules] Error 2 rm -f *.mod.c *.mod *.o .*.cmd *.ko *~ rm -rf /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187/tmp make -C /lib/modules/3.5.0-19-generic/build M=/home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187 modules make[1]: Entering directory `/usr/src/linux-headers-3.5.0-19-generic' CC [M] /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187/r8187_core.o In file included from /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187/r8187_core.c:64:0: /home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187/r8187.h:29:26: fatal error: linux/config.h: No such file or directory compilation terminated. make[2]: *** [/home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187/r8187_core.o] Error 1 make[1]: *** [_module_/home/me/Downloads/rtl8187_linux_26.1025.0328.2007/rtl8187] Error 2 make[1]: Leaving directory `/usr/src/linux-headers-3.5.0-19-generic' make: *** [modules] Error 2 Can somebody give me a hand finding out what I need to do to make my wifi card work? Update This is the output of the lsusb command lsusb Bus 003 Device 002: ID 147e:1000 Upek Biometric Touchchip/Touchstrip Fingerprint Sensor Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

    Read the article

  • obiee memory usage

    - by user554629
    Heap memory is a frequent customer topic. Here's the quick refresher, oriented towards AIX, but the principles apply to other unix implementations. 1. 32-bit processes have a maximum addressability of 4GB; usable application heap size of 2-3 GB.  On AIX it is controlled by an environment variable: export LDR_CNTRL=....=MAXDATA=0x080000000   # 2GB ( The leading zero is deliberate, not required )   1a. It is  possible to get 3.25GB  heap size for a 32-bit process using @DSA (Discontiguous Segment Allocation)     export LDR_CNTRL=MAXDATA=0xd0000000@DSA  # 3.25 GB 32-bit only        One side-effect of using AIX segments "c" and "d" is that shared libraries will be loaded privately, and not shared.        If you need the additional heap space, this is worth the trade-off.  This option is frequently used for 32-bit java.   1b. 64-bit processes have no need for the @DSA option. 2. 64-bit processes can double the 32-bit heap size to 4GB using: export LDR_CNTRL=....=MAXDATA=0x100000000  # 1 with 8-zeros    2a. But this setting would place the same memory limitations on obiee as a 32-bit process    2b. The major benefit of 64-bit is to break the binds of 32-bit addressing.  At a minimum, use 8GB export LDR_CNTRL=....=MAXDATA=0x200000000  # 2 with 8-zeros    2c.  Many large customers are providing extra safety to their servers by using 16GB: export LDR_CNTRL=....=MAXDATA=0x400000000  # 4 with 8-zeros There is no performance penalty for providing virtual memory allocations larger than required by the application.  - If the server only uses 2GB of space in 64-bit ... specifying 16GB just provides an upper bound cushion.    When an unexpected user query causes a sudden memory surge, the extra memory keeps the server running. 3.  The next benefit to 64-bit is that you can provide huge thread stack sizes for      strange queries that might otherwise crash the server.      nqsserver uses fast recursive algorithms to traverse complicated control structures.    This means lots of thread space to hold the stack frames.    3a. Stack frames mostly contain register values;  64-bit registers are twice as large as 32-bit          At a minimum you should  quadruple the size of the server stack threads in NQSConfig.INI          when migrating from 32- to 64-bit, to prevent a rogue query from crashing the server.           Allocate more than is normally necessary for safety.    3b. There is no penalty for allocating more stack size than you need ...           it is just virtual memory;   no real resources  are consumed until the extra space is needed.    3c. Increasing thread stack sizes may require the process heap size (MAXDATA) to be increased.          Heap space is used for dynamic memory requests, and for thread stacks.          No performance penalty to run with large heap and thread stack sizes.           In a 32-bit world, this safety would require careful planning to avoid exceeding 2GM usable storage.     3d. Increasing the number of threads also may require additional heap storage.          Most thread stack frames on obiee are allocated when the server is started,          and the real memory usage increases as threads run work. Does 2.8GB sound like a lot of memory for an AIX application server? - I guess it is what you are accustomed to seeing from "grandpa's applications". - One of the primary design goals of obiee is to trade memory for services ( db, query caches, etc) - 2.8GB is still well under the 4GB heap size allocated with MAXDATA=0x100000000 - 2.8GB process size is also possible even on 32-bit Windows applications - It is not unusual to receive a sudden request for 30MB of contiguous storage on obiee.- This is not a memory leak;  eventually the nqsserver storage will stabilize, but it may take days to do so. vmstat is the tool of choice to observe memory usage.  On AIX vmstat will show  something that may be  startling to some people ... that available free memory ( the 2nd column ) is always  trending toward zero ... no available free memory.  Some customers have concluded that "nearly zero memory free" means it is time to upgrade the server with more real memory.   After the upgrade, the server again shows very little free memory available. Should you be concerned about this?   Many customers are !!  Here is what is happening: - AIX filesystems are built on a paging model.   If you read/write a  filesystem block it is paged into memory ( no read/write system calls ) - This filesystem "page" has its own "backing store" on disk, the original filesystem block.   When the system needs the real memory page holding the file block, there is no need to "page out".    The page can be stolen immediately, because the original is still on disk in the filesystem. - The filesystem  pages tend to collect ... every filesystem block that was ever seen since    system boot is available in memory.  If another application needs the file block, it is retrieved with no physical I/O. What happens if the system does need the memory ... to satisfy a 30MB heap request by nqsserver, for example? - Since the filesystem blocks have their own backing store ( not on a paging device )   the kernel can just steal any filesystem block ... on a least-recently-used basis   to satisfy a new real memory request for "computation pages". No cause for alarm.   vmstat is accurately displaying whether all filesystem blocks have been touched, and now reside in memory.   Back to nqsserver:  when should you be worried about its memory footprint? Answer:  Almost never.   Stop monitoring it ... stop fussing over it ... stop trying to optimize it. This is a production application, and nqsserver uses the memory it requires to accomplish the job, based on demand. C'mon ... never worry?   I'm from New York ... worry is what we do best. Ok, here is the metric you should be watching, using vmstat: - Are you paging ... there are several columns of vmstat outputbash-2.04$ vmstat 3 3 System configuration: lcpu=4 mem=4096MB kthr    memory              page              faults        cpu    ----- ------------ ------------------------ ------------ -----------  r  b    avm   fre  re  pi  po  fr   sr  cy  in   sy  cs us sy id wa  0  0 208492  2600   0   0   0   0    0   0  13   45  73  0  0 99  0  0  0 208492  2600   0   0   0   0    0   0   9   12  77  0  0 99  0  0  0 208492  2600   0   0   0   0    0   0   9   40  86  0  0 99  0 avm is the "available free memory" indicator that trends toward zerore   is "re-page".  The kernel steals a real memory page for one process;  immediately repages back to original processpi  "page in".   A process memory page previously paged out, now paged back in because the process needs itpo "page out" A process memory block was paged out, because it was needed by some other process Light paging activity ( re, pi, po ) is not a concern for worry.   Processes get started, need some memory, go away. Sustained paging activity  is cause for concern.   obiee users are having a terrible day if these counters are always changing. Hang on ... if nqsserver needs that memory and I reduce MAXDATA to keep the process under control, won't the nqsserver process crash when the memory is needed? Yes it will.   It means that nqsserver is configured to require too much memory and there are  lots of options to reduce the real memory requirement.  - number of threads  - size of query cache  - size of sort But I need nqsserver to keep running. Real memory is over-committed.    Many things can cause this:- running all application processes on a single server    ... DB server, web servers, WebLogic/WebSphere, sawserver, nqsserver, etc.   You could move some of those to another host machine and communicate over the network  The need for real memory doesn't go away, it's just distributed to other host machines. - AIX LPAR is configured with too little memory.     The AIX admin needs to provide more real memory to the LPAR running obiee. - More memory to this LPAR affects other partitions. Then it's time to visit your friendly IBM rep and buy more memory.

    Read the article

  • CodePlex Daily Summary for Friday, May 09, 2014

    CodePlex Daily Summary for Friday, May 09, 2014Popular ReleasesQuickMon: Version 3.9: First official release of the PowerShell script Collector. Corrective script can now also be PowerShell scripts! There are a couple of internal bugfixes to the core components as well. e.g. Overriding remote host setting now applies to ALL child collectors Main UI app now indicates (in Window title) if there are changes that needs to be saved. Polling frequency can be adjusted by 'slide bar' Note: If you have issues with the new PowerShell script collector please see my post about issu...51Degrees.mobi - Mobile Device Detection and Redirection: 2.1.21.4: One Click Install from NuGet Changes to Version 2.1.21.4The ReadStrings method of the binary reader will now convert strings straight from ASCII as they’re now being written in the data file as ASCII only. The ReadCollection method of the binary reader will now return arrays of integers rather than generic lists to reduce memory consumption. This change has required some public methods to use IList rather the List types. 3rd party source code that accesses the library via these methods may...Media Companion: Media Companion MC3.597b: Thank you for being patient, againThere are a number of fixes in place with this release. and some new features added. Most are self explanatory, so check out the options in Preferences. Couple of new Features:* Movie - Allow save Title and Sort Title in Title Case format. * Movie - Allow save fanart.jpg if movie in folder. * TV - display episode source. Get episode source from episode filename. Fixed:* Movie - Added Fill Tags from plot keywords to Batch Rescraper. * Movie - Fixed TMDB s...SimCityPak: SimCityPak 0.3.0.0: Contains several bugfixes, newly identified properties and some UI improvements. Main new features UI overhaul for the main index list: Icons for each different index, including icons for different property files Tooltips for all relevant fields Removed clutter Identified hundreds of additional properties (thanks to MaxisGuillaume) - this should make modding gameplay easierSeal Report: Seal Report 1.4: New Features: Report Designer: New option to convert a Report Source into a Repository Source. Report Designer: New contextual helper menus to select, remove, copy, prompt elements in a model. Web Server: New option to expand sub-folders displayed in the tree view. Web Server: Web Folder Description File can be a .cshtml file to display a MVC View. Views: additional CSS parameters for some DIVs. NVD3 Chart: Some default configuration values have been changed. Issues Addressed:16 ...Magick.NET: Magick.NET 6.8.9.002: Magick.NET linked with ImageMagick 6.8.9.0.VidCoder: 1.5.22 Beta: Added ability to burn SRT subtitles. Updated to HandBrake SVN 6169. Added checks to prevent VidCoder from running with a database version newer than it expects. Tooltips in the Advanced Video panel now trigger on the field labels as well as the fields themselves. Fixed updating preset/profile/tune/level settings on changing video encoder. This should resolve some problems with QSV encoding. Fixed tunes and profiles getting set to blank when switching between x264 and x265. Fixed co...NuGet: NuGet 2.8.2: We will be releasing a 2.8.2 version of our own NuGet packages and the NuGet.exe command-line tool. The 2.8.2 release will not include updated VS or WebMatrix extensions. NuGet.Server.Extensions.dll needs to be used alongside NuGet-Signed.exe to provide the NuGet.exe mirror functionality.babelua: 1.5.3: V1.5.3 - 2014.5.6Stability improvement: support relative path when debugging lua files; improve variable view function in debugger; fix a bug that when a file is loaded at runtime , its breakpoints would not take effect; some other bug fix; New feature: improve tool windows color scheme to look better with different vs themes; comment/uncomment code block easily; some other improve;SmartStore.NET - Free ASP.NET MVC Ecommerce Shopping Cart Solution: SmartStore.NET 2.0.2: SmartStore.NET 2.0.2 is primarily a maintenance release for version 2.0.0, which has been released on April 04 2014. It contains several improvements & important fixes. BugfixesIMPORTANT FIX: Memory leak leads to OutOfMemoryException in application after a while Installation fix: some varchar(MAX) columns get created as varchar(4000). Added a migration to fix the column specs. Installation fix: Setup fails with exception Value cannot be null. Parameter name: stream Bugfix for stock iss...Channel9's Absolute Beginner Series: Windows Phone 8.1: Entire source code for Windows Phone 8.1 Absolute Beginner Series.BIDS Helper: BIDS Helper 1.6.6: This BIDS Helper beta release brings support for SQL Server 2014 and SSDTBI for Visual Studio 2013. (Note that SSDTBI for Visual Studio 2013 is currently unavailable to download from Microsoft. We are releasing BIDS Helper support to help those who downloaded it before it became unavailable, and we will recheck BIDS Helper 2014 is compatible after SSDTBI becomes available to download again.) BIDS Helper 2014 Beta Limitations: SQL Server 2014 support for Biml is still in progress, so this bet...Windows Phone IsoStoreSpy (a cool WP8.1 + WP8 Isolated Storage Explorer): IsoStoreSpy WP8.1 3.0.0.0 (Win8 only): 3.0.0.0 + WP8.1 & WP8 device allowed + Local, Roaming or Temp directory Selector for WindowsRuntime apps + Version number in the title :)CS-Script for Notepad++ (C# intellisense and code execution): Release v1.0.24.0: ShortcutMapping panel now allows direct modification of the shortcuts. Custom updater dropped support for MSI installation but it still allows downloading of MSI http://www.csscript.net/npp/codeplex/non_msi_update.pngProDinner - ASP.NET MVC Sample (EF5, N-Tier, jQuery): 8.2: upgrade to mvc 5 upgrade to ASP.net MVC Awesome 4.0, EF 6.1, latest jcrop, Windsor Castle etc. ability to show/hide the dog using tinymce for the feedback page mobile friendly uiASP.net MVC Awesome - jQuery Ajax Helpers: 4.0: version 4.0 ========================== - added InitPopup, InitPopupForm helpers, open initialized popups using awe.open(name, params) - added Tag or Tags for all helpers, usable in mod code - added popup aweclose, aweresize events - popups have api accessible via .data('api'), with methods open, close and destroy - all popups have .awe-popup class - popups can be grouped using .Group(string), only 1 popup in the same group can exist at the same time - added awebeginload event for...SEToolbox: SEToolbox 01.028.008 Release 2: Fixes for drag-drop copying. Added ship joiner, to rejoin a broken ship! Installation of this version will replace older version.ScreenToGif: Release 1.0: What's new: • Small UI tweaks everywhere. • You can add Text, Subtitles and Title Frames. • Processing the gif now takes less time. • Languages: Spanish, Italian and Tamil added. • Single .exe multi language. • Takes less time to apply blur and pixelated efect. • Restart button. • Language picker. (If the user wants to select a diferent language than the system's) • "Encoding Finished" page with a link to open the file. • GreenScreen unchanged pixels to save kilobytes. • "Check for Updates" t...Touchmote: Touchmote 1.0 beta 11: Changes Support for multiple monitor setup Additional settings for analog sticks More reliable pairing Bug fixes and improvementsPowerShell App Deployment Toolkit: PowerShell App Deployment Toolkit v3.1.2: Added Get-IniValue / Set-IniValue functions. Replaces Get-IniContent / Set-IniContent which were a bit unwieldy. The new functions are much easier to use. Added -Value parameter to Get-RegistryKey so that a specific registry value can be retrieved instead of the entire Key as an object Fixed Test-Battery to work with machines that can have multiple batteries Fixed issue where BlockExecution would fail if a Custom Temp Path was specified in the config file Updated examples with latest ...New ProjectsAgriComer: Este proyecto es creado con el objetivo inicial de ofrecer una herramienta integral para el comercio agrícola.AST - a tool for exploring windows kernel: A project for exploring windows kernel. It is consist of a Winform for presentation(by C#), and a windows driver(by C). VS2013 + WDK8.1 are required.CondimarSW: Sistema de ventasDeco Pattern: This project shows how the deco design pattern works.Geïntegreerd Project GH5: Geïntegreerd project .NET voor groep GH5Groep_EF4: PXL Groep EF4HttpRequestor: HttpRequestor is a nifty little tool for web developers, developed using Windows Forms, to make different types of HTTP requests to a web endpoint. IBehaviorPortable: This project has a single goal: to make it possible to write behaviors in a PCLKalkulator: Unit Test dan Coded UI TestLorenOS: LorenOS, an operating system based on MikeOSModernUI Extend: ModernUI ExtendPetite Scheme auto-execute pipeline: This program was originally created to avoid the steep learning curve of Emacs, and allow any editor to be used with ease for Chez Petite Scheme.projectgroep3.net: .net project for schoolReadable Athens (Hold-Cold Interactive Map): Demo application for Readable Athens art project Pins JPGs on map (using GPS EXIF info), shows at pin hover, louder noise closer to more text (*.jpg.txt OCRed)Training_Network_Messenger: Training network messengerTsLinq: This is a linq like implementation for typescript. Because typescript gets compiled into javascript, you can use this library for common javascript too.TSQL Smells SSDT: TSQL 'smells' finders TSQL Code can smell, it may work just fine but there can be hidden dangers held within. ??????-??????【??】????????: ?????????????????????????????,??????????,????,????,?????????、??????,??????。??????-??????【??】????????: ????????????????,?????????????? ??。????????、????、????、?????????? ???????。????-????【??】??????: ??????,??????:?????,?????,??????,??????????,????????。????????!?????-?????【??】???????: ?????????????????????????,????,????,??????????。???????????????,??,??,??????????,??????...?????-?????【??】?????????: ??????????????????????:????、????、??????????????,????????。????????!???????-???????【??】?????????: ???????????????????,???????????,??????????????,??????????,??????????????!???????-???????????: ????????????????,???????????????。???????????,??????:????、????、???????!?????-?????【??】???????: ??????????????????,?????????????,????,??????????,?????????????,?????,?????!??????-??????【??】??????????: ??????????????、????、????、??????、????、????????,????????、?????????,?????。??????-??????【??】??????????: ?????????????????,??????????????、???????、???????、???????、?????!??????-??????【??】??????????: ?????????????????,?????????????。?????????????????,???????,???????,?????,?????。????-????【??】??????: ???? ???? ???? ???? ???? ???? ???? ??????? ?????,????????????????.????-????【??】????????: ????????????????????????,???????????,????????,?????????????????????。??????-??????【??】????????: ????????????????,????,????,??????,????“????、????、????、????”????????,??????.??????-??????【??】??????????: ??????????????????????,????“???????,???????”?????,????????????!?????-?????【??】???????: ????????????,?????,???????????,???????,????,????,????,?????。?????-?????【??】?????????: ???????????????????,????????:??、??、???,?????????????????????!?????-?????【??】???????: ???????????????????,????????????????,????????????????,??????!??????-??????【??】????????: ????????????????????,??????????,????????、????,??????????,??????????。??????-??????【??】??????????: ????????????????、????,??100%????,??????,????????????,???????????!??????-??????【??】??????????: ????????????????6?,???????????????????????????,??????????????,?????????!????-????【??】????????: ??????????、???、??、??????????????????????????????,????????????????! ????-????【??】????????: ???????????????????????????、????、????、???????????,????,????!?????-?????【??】???????: ???????????,????,??????????? ???? ???? ?????????,???,??,?????!

    Read the article

  • CUDA linking error - Visual Express 2008 - nvcc fatal due to (null) configuration file

    - by Josh
    Hi, I've been searching extensively for a possible solution to my error for the past 2 weeks. I have successfully installed the Cuda 64-bit compiler (tools) and SDK as well as the 64-bit version of Visual Studio Express 2008 and Windows 7 SDK with Framework 3.5. I'm using windows XP 64-bit. I have confirmed that VSE is able to compile in 64-bit as I have all of the 64-bit options available to me using the steps on the following website: (since Visual Express does not inherently include the 64-bit packages) http://jenshuebel.wordpress.com/2009/02/12/visual-c-2008-express-edition-and-64-bit-targets/ I have confirmed the 64-bit compile ability since the "x64" is available from the pull-down menu under "Tools-Options-VC++ Directories" and compiling in 64-bit does not result in the entire project being "skipped". I have included all the needed directories for 64-bit cuda tools, 64 SDK and Visual Express (\VC\bin\amd64). Here's the error message I receive when trying to compile in 64-bit: 1>------ Build started: Project: New, Configuration: Release x64 ------ 1>Compiling with CUDA Build Rule... 1>"C:\CUDA\bin64\nvcc.exe" -arch sm_10 -ccbin "C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\bin" -Xcompiler "/EHsc /W3 /nologo /O2 /Zi /MT " -maxrregcount=32 --compile -o "x64\Release\template.cu.obj" "c:\Documents and Settings\All Users\Application Data\NVIDIA Corporation\NVIDIA GPU Computing SDK\C\src\CUDA_Walkthrough_DeviceKernels\template.cu" 1>nvcc fatal : Visual Studio configuration file '(null)' could not be found for installation at 'C:/Program Files (x86)/Microsoft Visual Studio 9.0/VC/bin/../..' 1>Linking... 1>LINK : fatal error LNK1181: cannot open input file '.\x64\Release\template.cu.obj' 1>Build log was saved at "file://c:\Documents and Settings\Administrator\My Documents\Visual Studio 2008\Projects\New\New\x64\Release\BuildLog.htm" 1>New - 1 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== Here's the simple code I'm trying to compile/run in 64-bit: #include <stdlib.h> #include <stdio.h> #include <string.h> #include <math.h> #include <cuda.h> void mypause () { printf ( "Press [Enter] to continue . . ." ); fflush ( stdout ); getchar(); } __global__ void VecAdd1_Kernel(float* A, float* B, float* C, int N) { int i = blockDim.x*blockIdx.x+threadIdx.x; if (i<N) C[i] = A[i] + B[i]; //result should be a 16x1 array of 250s } __global__ void VecAdd2_Kernel(float* B, float* C, int N) { int i = blockDim.x*blockIdx.x+threadIdx.x; if (i<N) C[i] = C[i] + B[i]; //result should be a 16x1 array of 400s } int main() { int N = 16; float A[16];float B[16]; size_t size = N*sizeof(float); for(int i=0; i<N; i++) { A[i] = 100.0; B[i] = 150.0; } // Allocate input vectors h_A and h_B in host memory float* h_A = (float*)malloc(size); float* h_B = (float*)malloc(size); float* h_C = (float*)malloc(size); //Initialize Input Vectors memset(h_A,0,size);memset(h_B,0,size); h_A = A;h_B = B; printf("SUM = %f\n",A[1]+B[1]); //simple check for initialization //Allocate vectors in device memory float* d_A; cudaMalloc((void**)&d_A,size); float* d_B; cudaMalloc((void**)&d_B,size); float* d_C; cudaMalloc((void**)&d_C,size); //Copy vectors from host memory to device memory cudaMemcpy(d_A,h_A,size,cudaMemcpyHostToDevice); cudaMemcpy(d_B,h_B,size,cudaMemcpyHostToDevice); //Invoke kernel int threadsPerBlock = 256; int blocksPerGrid = (N+threadsPerBlock-1)/threadsPerBlock; VecAdd1(blocksPerGrid, threadsPerBlock,d_A,d_B,d_C,N); VecAdd2(blocksPerGrid, threadsPerBlock,d_B,d_C,N); //Copy results from device memory to host memory //h_C contains the result in host memory cudaMemcpy(h_C,d_C,size,cudaMemcpyDeviceToHost); for(int i=0; i<N; i++) //output result from the kernel "VecAdd" { printf("%f ", h_C[i] ); printf("\n"); } printf("\n"); cudaFree(d_A); cudaFree(d_B); cudaFree(d_C); free(h_A); free(h_B); free(h_C); mypause(); return 0; }

    Read the article

  • Android daemon process

    - by J Andy
    Is it possible (without violating any licenses) to write a native C/C++ application on top of the Android OS and make it run as a daemon process? There are already several daemon process' running which one can see with the 'ps' command, the legal part concerns me the most. And also the lack of documentation on how to exactly do this. For the writing part, I guess one could use basic Linux programming concepts, since Android supports at least to some level the standard Posix API. To make it run as the phone boots, some modifications is of course required in init as well. I have no plans to have this app in the Android Market, so installing it manually to the phone is not a problem. As long as it does not require re-compiling the whole OS or kernel. I really appreciate all info on this topic, since there's isn't much available. Thanks.

    Read the article

  • How to do a timestamp comparison with JPA query?

    - by Robert
    We need to make sure only results within the last 30 days are returned for a JPQL query. An example follows: Date now = new Date(); Timestamp thirtyDaysAgo = new Timestamp(now.getTime() - 86400000*30); Query query = em.createQuery( "SELECT msg FROM Message msg "+ "WHERE msg.targetTime < CURRENT_TIMESTAMP AND msg.targetTime > {ts, '"+thirtyDaysAgo+"'}"); List result = query.getResultList(); Here is the error we receive: <openjpa-1.2.3-SNAPSHOT-r422266:907835 nonfatal user error org.apache.openjpa.persistence.ArgumentException: An error occurred while parsing the query filter 'SELECT msg FROM BroadcastMessage msg WHERE msg.targetTime < CURRENT_TIMESTAMP AND msg.targetTime {ts, '2010-04-18 04:15:37.827'}'. Error message: org.apache.openjpa.kernel.jpql.TokenMgrError: Lexical error at line 1, column 217. Encountered: "{" (123), after : "" Help!

    Read the article

  • Device Driver IRQL and Thread/Context Switches

    - by Christian Hoglund
    Hi, I'm new to Windows device driver programming. I know that certain operations can only be performed at IRQL PASSIVE_LEVEL. For example, Microsoft have this sample code of how to write to a file from a kernel driver: if (KeGetCurrentIrql() != PASSIVE_LEVEL) return STATUS_INVALID_DEVICE_STATE; Status = ZwCreateFile(...); My question is this: What is preventing the IRQL from being raised after the KeGetCurrentIrql() check above? Say a context or thread swithch occurs, couldn't the IRQL suddenly be DISPATCH_LEVEL when it gets back to my driver which would then result in a system crash? If this is NOT possible then why not just check the IRQL in the DriverEntry function and be done with it once for all?

    Read the article

  • A good machine learning technique to weed out good URLs from bad

    - by git-noob
    Hi, I have an application that needs to discriminate between good HTTP GET requests and bad. For example: http://somesite.com?passes=dodgy+parameter # BAD http://anothersite.com?passes=a+good+parameter # GOOD My system can make a binary decision about whether or not a URL is good or bad - but ideally I would like it to predict whether or not a previously unseen URL is good or bad. http://some-new-site.com?passes=a+really+dodgy+parameter # BAD I feel the need for a support vector machine (SVM) ... but I need to learn machine learning. Some questions: 1) Is an SVM appropriate for this task? 2) Can I train it with the raw URLs? - without explicitly specifying 'features' 3) How many URLs will I need for it to be good at predictions? 4) What kind of SVM kernel should I use? 5) After I train it, how do I keep it up to date? 6) How do I test unseen URLs again the SVM to decide whether it's good or bad? I

    Read the article

  • Error when importing com.google, com.android.internal.Telephony, etc.

    - by psyhclo
    Hey, I've downloaded the android source code for CallLog, Contacts, Dialing in this link http://android.git.kernel.org/?p=platform/packages/apps/Contacts.git;a=tree But now, when I try to import this package on Eclipse, imports like: com.google, com.android.internal.Telephony, com.android.internal.R, com.google.android.collect, android.provider.ContactsContract.Intents.UI, android.provider.ContactsContract.SearchSnippetColumns, android.provider.ContactsContract.ProviderStatus, android.provider.ContactsContract.ContactCounts, android.content.IContentService, android.provider.ContactsContract.Intents.UI And many other imports, show errors saying it cannot be resolved. So my question is, why it shows this errors? Why I cant implement it without this errors? I use the Google APIs, I've created the project from an existing source code, but I dont know why this happens. Thanks.

    Read the article

  • Accessing one process's memory contents from another module

    - by Fangkai Yang
    I am developing a virtual device driver such that the user can write to the driver a process' pid and a virtual address, and the module will use these two values to get the memory contents of the target process. I am wondering if there is any easy functions that can fetch user page's data at this virtual address. I have tried get_user but this is not possible because the modules executing get_user at another process's context. I also tried to use ptrace_readdata, however, it seems that the file at /kernel/ptrace.c leaves a function access_process_vm undefined and also I don't know how to compile the source code of my module with this file (the linker seaches file in /linux/include by default). I am wondering if there are any other solutions...

    Read the article

  • SSAS 2008 backup/restore fails with a GetOverlappedResult 'Insufficient system resources exist to co

    - by Anant Aneja
    Hi, On my SSAS 2008 instance if a backup/restore of any database is made to/from a UNC path I get an error : The following system error occurred from a call to GetOverlappedResult for Physical file: '\server\share\OLAPDB.abf', Logical file: '' : Insufficient system resources exist to complete the requested service. . Server: The operation has been cancelled. (Microsoft.AnalysisServices) Creating/copying/moving a file on the share of any size on the share using explorer or the command prompt works. The most useful link I could find is : http://www.tech-archive.net/Archive/Development/microsoft.public.win32.programmer.kernel/2004-07/0475.html Can anyone shed more light on what could be causing this error ? (I've posted the same question on the SSAS forums - just a heads up)

    Read the article

  • Passing parameters between interrupt handlers on a Cortex-M3 ...

    - by Captain NedD
    I'm building a light kernel for a Cortex-M3. From a high priority interrupt I'd like to invoke some code to run in a lower priority interrupt and pass some parameters along. I don't want to use a queue to post work to the lower priority interrupt. I just have a buffer and size to pass to it. In the proramming manual it says that the SVC interrupt handler is synchronous which presumably means that if you invoke it from an interrupt that's a lower priority than SVC's handler it gets called immediately (the upshot of this being that you can pass parameters to it as though it were a function call (a little like the BIOS calls in MS-DOS)). I'd like to do it the other way: passing parameters from a high priority interrupt to a lower priority one (at the moment I'm doing it by leaving the parameters in a fixed location in memory). What's the best way to do this (if at all possible)? Thanks,

    Read the article

  • Access violation after GetInterface/QueryInterface in Delphi

    - by W55tKQbuRu28Q4xv
    Hi everyone! First, I'm very new in Delphi and COM, but I should build COM application in Delphi. I read a lot of articles and notes on the internets, but COM and COM in Delphi are still not clear to me. My sources - http://www.everfall.com/paste/id.php?wisdn8hyhzkt (about 80 lines). I try to make a COM Interface and Impl class - it works if I call an interface method from Delphi (I create an impl object via TestClient.Create), but if I try to create an object from outer world (from Java, via com4j) my application crashed with following exception: Project Kernel.exe raised exception class $C0000005 with message 'access violation at 0x00000002: read of address 0x00000002'. If I set a breakpoint in QueryInterface - it breaks, but when I come out from function - all crashes. What I'm doing wrong? What I still missing? What I can/should read about COM (in Delphi) to avoid dumb questions like this?

    Read the article

  • CUDA compare arrays

    - by user315511
    Hello. Trying to make an app that will compare 1-to-multiple bitmaps. there is one reference bitmap and multiple other bitmaps. Result from each compare should be new bitmap with diffs. Maybe comparing bitmaps rather as textures than arrays? My biggest problem is making kernel accept more than one input pointer, and how to compare the data.. extern "C" __global__ void compare(float *odata, float *idata, int width, int height) works and following does not (i call the function with enough params) extern "C" __global__ void compare(float *odata, float *idata, float *idata2, int width, int height)

    Read the article

  • Bluescreen 0x0000003B during DownloadFileAsync?

    - by SeveQ
    Hello again, I've run into a problem with an application I'm developing in C#/.NET. A problem I can't trace down because it causes my system to crash with a BSOD. Here's the minidump: 060310-27066-01.dmp 03.06.2010 19:47:39 SYSTEM_SERVICE_EXCEPTION 0x0000003b 00000000c0000005 fffff8000306d4d0 fffff8800b107640 0000000000000000 ntoskrnl.exe ntoskrnl.exe+70600 NT Kernel & System Microsoft® Windows® Operating System Microsoft Corporation 6.1.7600.16539 (win7_gdr.100226-1909) x64 C:\Windows\Minidump\060310-27066-01.dmp 4 15 7600 It's not related specifically to DownloadFileAsync. Other methods of the System.Net assembly classes related to HTTP download also make my system crash. I really hope someone can help me with this. Just for info: other apps (browsers etc.) that download files work like a charm. If you need further information don't hesitate to ask! Thanks!

    Read the article

< Previous Page | 481 482 483 484 485 486 487 488 489 490 491 492  | Next Page >