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  • What do you use to play sound in iPhone games?

    - by zoul
    Hello! I have a performance-intensive iPhone game I would like to add sounds to. There seem to be about three main choices: (1) AVAudioPlayer, (2) Audio Queues and (3) OpenAL. I’d hate to write pages of low-level code just to play a sample, so that I would like to use AVAudioPlayer. The problem is that it seems to kill the performace – I’ve done a simple measuring using CFAbsoluteTimeGetCurrent and the play message seems to take somewhere from 9 to 30 ms to finish. That’s quite miserable, considering that 25 ms == 40 fps. Of course there is the prepareToPlay method that should speed things up. That’s why I wrote a simple class that keeps several AVAudioPlayers at its disposal, prepares them beforehand and then plays the sample using the prepared player. No cigar, still it takes the ~20 ms I mentioned above. Such performance is unusable for games, so what do you use to play sounds with a decent performance on iPhone? Am I doing something wrong with the AVAudioPlayer? Do you play sounds with Audio Queues? (I’ve written something akin to AVAudioPlayer before 2.2 came out and I would love to spare that experience.) Do you use OpenAL? If yes, is there a simple way to play sounds with OpenAL, or do you have to write pages of code? Update: Yes, playing sounds with OpenAL is fairly simple.

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  • LINQ to SQL - Lightweight O/RM?

    - by CoffeeAddict
    I've heard from some that LINQ to SQL is good for lightweight apps. But then I see LINQ to SQL being used for Stackoverflow, and a bunch of other .coms I know (from interviewing with them). Ok, so is this true? for an e-commerce site that's bringing in millions and you're typically only doing basic CRUDs most the time with the exception of an occasional stored proc for something more complex, is LINQ to SQL complete enough and performance-wise good enough or able to be tweaked enough to run happily on an e-commerce site? I've heard that you just need to tweak performance on the DB side when using LINQ to SQL for a better approach. So there are really 2 questions here: 1) Meaning/scope/definition of a "Lightweight" O/RM solution: What the heck does "lightweight" mean when people say LINQ to SQL is a "lightweight O/RM" and is that true??? If this is so lightweight then why do I see a bunch of huge .coms using it? Is it good enough to run major .coms (obviously it looks like it is) and what determines what the context of "lightweight" is...it's such a generic statement. 2) Performance: I'm working on my own .com and researching different O/RMs. I'm not really looking at the Entity Framework (yet), just want to figure out the LINQ to SQL basics here and determine if it will be efficient enough for me. The problem I think is you can't tweak or control the SQL it generates...

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  • Get Image Source URLs from a Different Page Using JS

    - by SDD
    Everyone: I'm trying to grab the source URLs of images from one page and use them in some JavaScript in another page. I know how to pull in images using JQuery .load(). However, rather than load all the images and display them on the page, I want to just grab the source URLs so I can use them in a JS array. Page 1 is just a page with images: <html> <head> </head> <body> <img id="image0" src="image0.jpg" /> <img id="image1" src="image1.jpg" /> <img id="image2" src="image2.jpg" /> <img id="image3" src="image3.jpg" /> </body> </html> Page 2 contains my JS. (Please note that the end goal is to load images into an array, randomize them, and using cookies, show a new image on page load every 10 seconds. All this is working. However, rather than hard code the image paths into my javascript as shown below, I'd prefer to take the paths from Page 1 based on their IDs. This way, the images won't always need to be titled "image1.jpg," etc.) <script type = "text/javascript"> var days = 730; var rotator = new Object(); var currentTime = new Date(); var currentMilli = currentTime.getTime(); var images = [], index = 0; images[0] = "image0.jpg"; images[1] = "image1.jpg"; images[2] = "image2.jpg"; images[3] = "image3.jpg"; rotator.getCookie = function(Name) { var re = new RegExp(Name+"=[^;]+", "i"); if (document.cookie.match(re)) return document.cookie.match(re)[0].split("=")[1]; return''; } rotator.setCookie = function(name, value, days) { var expireDate = new Date(); var expstring = expireDate.setDate(expireDate.getDate()+parseInt(days)); document.cookie = name+"="+value+"; expires="+expireDate.toGMTString()+"; path=/"; } rotator.randomize = function() { index = Math.floor(Math.random() * images.length); randomImageSrc = images[index]; } rotator.check = function() { if (rotator.getCookie("randomImage") == "") { rotator.randomize(); document.write("<img src=" + randomImageSrc + ">"); rotator.setCookie("randomImage", randomImageSrc, days); rotator.setCookie("timeClock", currentMilli, days); } else { var writtenTime = parseInt(rotator.getCookie("timeClock"),10); if ( currentMilli > writtenTime + 10000 ) { rotator.randomize(); var writtenImage = rotator.getCookie("randomImage") while ( randomImageSrc == writtenImage ) { rotator.randomize(); } document.write("<img src=" + randomImageSrc + ">"); rotator.setCookie("randomImage", randomImageSrc, days); rotator.setCookie("timeClock", currentMilli, days); } else { var writtenImage = rotator.getCookie("randomImage") document.write("<img src=" + writtenImage + ">"); } } } rotator.check() </script> Can anyone point me in the right direction? My hunch is to use JQuery .get(), but I've been unsuccessful so far. Please let me know if I can clarify!

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  • Low Throughput on Windows Named Pipe Over WAN

    - by MichaelB76
    I'm having problems with low performance using a Windows named pipe. The throughput drops off rapidly as the network latency increases. There is a roughly linear relationship between messages sent per second and round trip time. It seems that the client must ack each message before the server will send the next one. This leads to very poor performance, I can only send 5 (~100 byte) messages per second over a link with an RTT of 200 ms. The pipe is asynchronous, using multiple overlapped write operations (and multiple overlapped reads at the client end), but this is not improving throughput. Is it possible to send messages in parallel over a named pipe? The pipe is created using PIPE_TYPE_MESSAGE, would PIPE_READMODE_BYTE work better? Is there any other way I can improve performance? This is a deployed solution, so I can't simply replace the pipe with a socket connection (I've read that Windows named pipe aren't recommended for use over a WAN, and I'm wondering if this is why). I'd be grateful for any help with this matter.

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  • Limiting object allocation over multiple threads

    - by John
    I have an application which retrieves and caches the results of a clients query. The client then requests different chunks of data and the application sends the relevant results and removes them from the cache. A new requirement for this application is that there needs to be a run-time configurable maximum number of results which may be cached. I've taken the naive approach and implemented this by using a counter under a lock which is incremented every time a result is cached and decremented whenever a result is removed from the cache. Unfortunately, this has drastically reduced the applications performance when processing a large number of concurrent requests. I have tried both a critical section lock and spin-lock; the performance improves a bit with a spin-lock, but is still unacceptably slow. Is there a better way to solve this problem which may improve performance? Right now I have a thread pool that services requests and each request is tied to a Request object which stores that cached results for that particular request. Here is a simplified pseudo code version of my current implementation: void ResultCallback( Result result, Request *request ) { lock totalResultsCached lock cachedLimit if( totalResultsCached + 1 > cachedLimit ) { unlock cachedLimit unlock totalResultsCached //cancel the request return; } ++totalResultsCached; unlock cachedLimit unlock totalResultsCached request.add(result) } void SendResults( int resultsToSend, Request *request ) { while ( resultsToSend > 0 ) { send(request.remove()) lock totalResultsCached --totalResultsCached unlock totalResultsCached --resultsToSend; } }

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  • Storing C++ templated objects as same type

    - by JaredC
    I have a class that is a core component of a performance sensitive code path, so I am trying to optimize it as much as possible. The class used to be: class Widget { Widget(int n) : N(n) {} .... member functions that use the constant value N .... const int N; // just initialized, will never change } The arguments to the constructor are known at compile time, so I have changed this class to a template, so that N can be compiled into the functions: template<int N> class Widget { .... member functions that use N .... } I have another class with a method: Widget & GetWidget(int index); However, after templating Widget, each widget has a different type so I cannot define the function like this anymore. I considered different inheritance options, but I'm not sure that the performance gain from the template would outweigh the cost of inherited function invocations. SO, my question is this: I am pretty sure I want the best of both worlds (compile-time / run-time), and it may not be possible. But, is there a way to gain the performance of knowing N at compile time, but still being able to return Widgets as the same type? Thanks!

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  • Windows web server and SQL Server on same dedicated server

    - by asinc
    I'm currently trying to decide on the best approach to handle hosting a few moderate traffic websites for production e-commerce and online applications. We'd like to move to a dedicated server and are looking at this as the most likely machine: Quad Core Intel Core2Quad Q9550 Processor, 2.83 Ghz X 4, 4 GB Kingston Ram This would run Windows Web Server 2008 R2 x64 and potentially also Sql Server Web 2008 and SmarterMail server. Given that we already pay for a high-end VPS for development, testing, shared version control we'd like to avoid going with two servers for production. We'd like to avoid using shared sql server hosting and have thought of using the development server as the database server as an option too - but potentially a security risk due to use for development by internal and contract users. The questions are: - Do you feel there would be performance degradation by running this on the same machine? - Are there significant issues to be concerned about if we do this? We understand that best practice would be to run separate db and app servers but the volume of traffic is currently not that high and adding another server just for database is currently too costly. - What are others doing out there? Alternatively, would you recommend instead going with two separate VPS servers with 2GB RAM each on Hyper-v which would be about the same cost as the single dedicated server above? Thanks!

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  • How to compare old laptop to new laptop?

    - by Lasse V. Karlsen
    I hope this question doesn't get closed at once :) I have an old laptop, a Compaq NC4200, which is going its final laps around the track these days. Battery is dead, and everything kinda runs slow. It also has only 1GB of memory, and even though I don't know if it can take more, I probably wouldn't be able to get hold of any that matches without having to special order it. The size, however, has been ideal for my usage pattern, so I'm looking to replace it with a similarly sized laptop, at least in the same size category. However, it's been a while since I tried keeping track of CPUs, so I have a question. The old laptop has a Intel Pentium M 760 1.86GHz processor. One laptop I found online has a Intel Pentium SU4100 1.3GHz dual-core. This type of processor seems to be quite common in the price and size-range I've been looking. What kind of relative performance boost could I expect from the old one to the new one? I am not expecting a "about 7.45x speed", but some indication would be nice. For instance, dual-core tells me it might be akin to 2.6GHz, but I assume I can't simply compare 1.86GHz to 2.6GHz and expect the new one to run about 1.4x as fast, I expect more these days. Or is that unrealistic for this kind of processor? Do I need to up my price range and go for a 2+ GHz processor?

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  • How to set shmall, shmmax, shmni, etc ... in general and for postgresql

    - by jpic
    I've used the documentation from PostgreSQL to set it for example this config: >>> cat /proc/meminfo MemTotal: 16345480 kB MemFree: 1770128 kB Buffers: 382184 kB Cached: 10432632 kB SwapCached: 0 kB Active: 9228324 kB Inactive: 4621264 kB Active(anon): 7019996 kB Inactive(anon): 548528 kB Active(file): 2208328 kB Inactive(file): 4072736 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 3432 kB Writeback: 0 kB AnonPages: 3034588 kB Mapped: 4243720 kB Shmem: 4533752 kB Slab: 481728 kB SReclaimable: 440712 kB SUnreclaim: 41016 kB KernelStack: 1776 kB PageTables: 39208 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 8172740 kB Committed_AS: 14935216 kB VmallocTotal: 34359738367 kB VmallocUsed: 399340 kB VmallocChunk: 34359334908 kB HardwareCorrupted: 0 kB AnonHugePages: 456704 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 12288 kB DirectMap2M: 16680960 kB >>> ipcs -l ------ Shared Memory Limits -------- max number of segments = 4096 max seg size (kbytes) = 4316816 max total shared memory (kbytes) = 4316816 min seg size (bytes) = 1 ------ Semaphore Limits -------- max number of arrays = 128 max semaphores per array = 250 max semaphores system wide = 32000 max ops per semop call = 32 semaphore max value = 32767 ------ Messages Limits -------- max queues system wide = 31918 max size of message (bytes) = 8192 default max size of queue (bytes) = 16384 sysctl.conf extract: kernel.shmall = 1079204 kernel.shmmax = 4420419584 postgresql.conf non defaults: max_connections = 60 # (change requires restart) shared_buffers = 4GB # min 128kB work_mem = 4MB # min 64kB wal_sync_method = open_sync # the default is the first option checkpoint_segments = 16 # in logfile segments, min 1, 16MB each checkpoint_completion_target = 0.9 # checkpoint target duration, 0.0 - 1.0 effective_cache_size = 6GB Is this appropriate ? If not (or not necessarily), in which case would it be appropriate ? We did note nice performance improvements with this config, how would you improve it ? How should kernel memory management parameters be set ? Can anybody explain how to really set them from the ground up ?

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  • big speed difference on a network link with and without VPN tunnel

    - by xirtyllo
    Scenario: We have a network link between two offices. The link is provided by a third party company through a VLAN on their network, but to us it is totally transparent -as if we had a simple ethernet cable going from one location to the other-. We have one router at each side of the link, with 3 VPN tunnels in between the two. The test: When I test the speed of the network link with the routers in place, with one laptop directly connected to the router on each side, I consistently get ~30/35Mbps. But if I take out the routers and I test the link connecting the laptops directly to the ethernet cable at each side, I consistently get ~85/88Mbps. It's quite a big performance hit, and I would tend to think that the VPN tunnels are responsible for the slow down. Is it normal that this configuration (two routers with three VPN tunnels between them) takes away so much bandwidth? More info: The encryption algorithm used for the VPN tunnels is AES128. The routers model is Zyxel USG200 and Zyxel USG1000, and their CPU, memory, and storage use is well within normal limits. The nominal bandwidth of the network link is 100Mbps. The network link in question is supplied by a third party company (the building in between our two offices). Basically it passes through their network as a VLAN, but the VLAN is completely transparent to us (e.g. no configuration required on our side, just like one single cable from end to end). Unfortunately (or maybe fortunately) I cannot directly test different routers configurations as I'm not the person in charge of it.

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  • SQL Server slow in production environment

    - by Lieven Cardoen
    I have a weird problem in a customer's production environment. I can't give any details on the infrastructure, except that SQL server runs on a virtual server. The data, log and filestream file are on another storage server (data and filestream together and log on a separate server). In our local Test environment, there's one particular query that executes with these durations: first we clear the cache 300ms (First time it takes longer, but from then on it's cached.) 20ms 15ms 17ms In the customer's production environment, the SQL Server is more powerful, these are the durations (I didn't have the rights to clear the cache. Will try this tomorrow). 2500ms 2600ms 2400ms The servers in the customer's production environment are more powerful but they do have virtual servers (we don't). What could be the cause... Not enough memory? Fragmentation? Physical storage? How would you tackle this performance problem? EDIT: Some people have asked me if the data set is equal and it is. I restored their database on our environment. It's true that this was the first thing I looked at. (@Everyone: I added the edit because it will be the first thing that many will think off).

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  • Win 7 running slowly with low CPU usage and memory

    - by guywhoneedsahand
    I have a relatively new (under 2 yrs old) windows 7 machine. It has 9GB of RAM, and an i7 core CPU (930 @ 2.8GHz w/ 8 CPUs). After about 8 months since a clean install, I noticed my computer was running slowly. I figure it was fragmentation etc, and I did a complete wipe & clean reinstall. However, my problems are somehow persisting. The computer is running painfully slowly (but in leaps and bounds - sometimes it will work fine for 3 hrs, then suddenly freeze up just from clicking the start button). The 'freezes' happen randomly - not during any especially intensive computing. I initially thought something might be eating through my CPU and/or Memory, but Task Manager indicates that neither the CPU or Memory spike. In fact, even during serious lag, CPU usage remains at less than 5% and Memory at ~ 1.5GB. It's beyond me why a fresh install on a powerful machine is performing so poorly... and it certainly is frustrating! What could be causing the poor performance, and what can I do to fix it?

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  • Eclipse grinds to a halt when building workspace

    - by Chris Thompson
    Hi all, This is a bit of a vague question because, frankly, I don't even know where to begin diagnosing the issue. My eclipse (Galileo) installation grinds to a complete halt when it's building the workspace -- to the point where I can't even type. I know the Android SDK I have installed is a major culprit because I can watch the memory usage go through the roof (through the built-in heap monitor) when the Android SDK content loader starts up. Every time I save a file though, the program just stops. The message at the bottom of the screen says Building workspace (74%) and sits there for about 30 or so seconds before completing and returning the performance to normal. I have a few other plugins installed (Maven, SVN, etc) but I'm assuming the main issue is Android. Has anybody had similar issues or any luck correcting this sort of problem? If there's anymore information you think would be helpful, just let me know...I didn't want to do a core dump on this question... I'm running it on Windows 7 64-bit for what it's worth. Thanks! Chris

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  • What is optimal hardware configuration for heavy load LAMP application

    - by Piotr K.
    I need to run Linux-Apache-PHP-MySQL application (Moodle e-learning platform) for a large number of concurrent users - I am aiming 5000 users. By concurrent I mean that 5000 people should be able to work with the application at the same time. "Work" means not only do database reads but writes as well. The application is not very typical, since it is doing a lot of inserts/updates on the database, so caching techniques are not helping to much. We are using InnoDB storage engine. In addition application is not written with performance in mind. For instance one Apache thread usually occupies about 30-50 MB of RAM. I would be greatful for information what hardware is needed to build scalable configuration that is able to handle this kind of load. We are using right now two HP DLG 380 with two 4 core processors which are able to handle much lower load (typically 300-500 concurrent users). Is it reasonable to invest in this kind of boxes and build cluster using them or is it better to go with some more high-end hardware? I am particularly curious how many and how powerful servers are needed (number of processors/cores, size of RAM) what network equipment should be used (what kind of switches, network cards) any other hardware, like particular disc storage solutions, etc, that are needed Another thing is how to put together everything, that is what is the most optimal architecture. Clustering with MySQL is rather hard (people are complaining about MySQL Cluster, even here on Stackoverflow).

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  • How to compare old CPU to new CPU?

    - by Lasse V. Karlsen
    I hope this question doesn't get closed at once :) I have an old laptop, a Compaq NC4200, which is going its final laps around the track these days. Battery is dead, and everything kinda runs slow. It also has only 1GB of memory, and even though I don't know if it can take more, I probably wouldn't be able to get hold of any that matches without having to special order it. The size, however, has been ideal for my usage pattern, so I'm looking to replace it with a similarly sized laptop, at least in the same size category. However, it's been a while since I tried keeping track of CPUs, so I have a question. The old laptop has a Intel Pentium M 760 1.86GHz processor. One laptop I found online has a Intel Pentium SU4100 1.3GHz dual-core. This type of processor seems to be quite common in the price and size-range I've been looking. What kind of relative performance boost could I expect from the old one to the new one? I am not expecting a "about 7.45x speed", but some indication would be nice. For instance, dual-core tells me it might be akin to 2.6GHz, but I assume I can't simply compare 1.86GHz to 2.6GHz and expect the new one to run about 1.4x as fast, I expect more these days. Or is that unrealistic for this kind of processor? Do I need to up my price range and go for a 2+ GHz processor?

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  • What do different patterns mean in Windows 8 file copy dialog

    - by MainMa
    When copying or extracting files, Windows 8 shows the chart with the speed of the operation. I noticed several patterns: Randomness, High speed at the beginning, then low speed during the most part of the operation, Mostly constant speed. 1. Randomness/nice mountains. 2. High speed at the beginning, then low speed during the most part of the operation. 3. Low speed at the beginning, then high speed during the most part of the operation. (Similar to the previous image, but inverted) 3. Mostly constant speed. (Same as previous image, but without the fast start) I'm curious, what each of those patterns mean? Do some indicate that there may be a problem with hard disk performance? Why the nearly constant speed is so rare, even when copying a single large file from and to a spinning drive, or when copying a single large file or a bunch of small files from and to an SSD?

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  • Request bursting from web application Load Tests

    - by MaseBase
    I'm migrating our web and database hosting to a new environment on all new machines. I've recently performed a Load Test using WAPT to generate load from multiple distributed clients. The server has plenty of room to handle the traffic load, but I'm seeing an odd pattern of incoming traffic during the load tests. Here is the gist of our setup: Firewall server running MS Forefront TMG 2010 on Win 2k8 server Request routing done by IIS Application Request Routing on firewall machine Web server is a Hyper-V VM on the Database server (which is the host OS) These machines are hefty with dual-CPU's with six cores (12 total procs) Web server running IIS 7.5 Web applications built in ASP.NET 2.0, with 1 ISAPI filter (Url Rewrite) in front What I'm seeing during the load tests is that the requests all come through in bursts. Even though I have 7 different distributed clients sending traffic loads, the requests come through about 300-500 requests at a time. The performance monitor shows nearly all of the counters moving through this pattern, where a burst of requests comes in the req/sec jumps to 70, the queued requests jumps to 500, the current requests jumps up, the CPU jumps up, everything. Then once it's handled that group of requests, it has a lull for nearly 10 seconds where nearly nothing is happening. 0-5 req/sec, 0 queued requests, minimal CPU usage. Then after 10 seconds of inactivity, another burst comes through, spiking all of the counters once again. What I can't figure out is why the requests are coming through in bursts when I know that the load being generated is not sent that way, especially considering the various load-generating clients sending traffic all in different intervals with random think time's between each request. Is there something in the layers between Hyper-V or perhaps in the hardware which might cause this coalesce of requests together? Here is what i'm looking at, the highlighted metric is Requests/sec, but the others critical counter go with it: Requests Queued (which I'd obviously like to keep as close to 0 as possible). Any ideas on this?

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  • Load Testing a Security/Gateway Appliance

    - by Joel Coel
    In a couple weeks I will load testing a security/gateway appliance. We're a small residential college, and that "residential" means the traffic moving through the appliance is a bit like the Wild West. We have everything from Facebook to World of Warcraft, BitTorrent to Netflix, or Halo to YouTube... basically anything you might find in the home of a high-school or college aged person. Somewhere in there some real academic work gets done as well. We rely on our current appliance for traffic shaping, antivirus, malware filtering, intrusion detection on our servers, logging and abuse reporting, and even some content filtering. All this puts a decent load when we have students around, and I'm concerned about the ability of the new candidate to keep up. On paper it should handle things, but I'm worried. Prior experience is that vendors greatly over-report what an appliance can handle. The product also includes a licensed session limit, and I'm also worried that just a few misbehaving students could unwittingly bring us to that limit and cause service disruptions. I need to know this will work for our campus in order to commit to it. Going a performance level higher in that product takes the pricing way out of line with what we expect and have done in the past. What I need is a good way to load test this guy. My problem is that our current level of summer traffic is less than one percent of what it will be when students come back just six weeks from now. Any ideas on how to really stress this thing and see what it can do, in a way that will give me some clear ideas o. How that will scale for our campus? For the curious, I'm looking at a Watchguard 515, but it could be anything. If I were evaluating a competitor, I'd ask the same question.

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  • How to make a huge ram drive?

    - by Brandon Moore
    At my old job when a report was needed I could sit down with someone and pull up results and get immediate feedback, and then refine my queries and ultimately have the data we needed, in the format we needed within 30-90 minutes. I just started working for a new company with a database containing millions of records and I spent my whole 8 hours making a report that I feel I could have made in less than 2 hours if it were not for the massive amount of data the queries are working with, and the fact that I couldn't ask the person needing the data to sit down with me and give me feedback as I pulled up results as I am used to. So I am trying to think of how we can make the server faster... much faster, so that I can have the same level of productivity I'm used to. One thought that just came to mind is that memory is so cheap these days, and by my calculations I could buy 10 8gig ram sticks for 1000 bucks. What I have never heard of though is a device that would let me combine these into a huge ram drive. So I'd like to know if any such device exists, and if not what is the largest ram drive I could realistically make and how would I go about doing so? EDIT: To you guys who are saying the database shema needs to be analyzed... you can't make a query such as "Select f1, f2, f3, etc from SomeTable" run any faster by normalizing or indexing the table. What I'm talking about IS ABSOLUTELY a need for improved performance at the hardware level. I am used to having results come back to me in a few seconds, not a few minutes or much less a half an hour. Maybe that's what you guys are used to who have 100 billion record tables and you feel like that's fast, but I'm looking for results back from tables with about 10 million records to come back to me withing less than half a minute TOPS.

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  • Disk IO slow on ESXi, even slower on a VM (freeNAS + iSCSI)

    - by varesa
    I have a server with ESXi 5 and iSCSI attached network storage(4x1Tb Raid-Z on freenas 8.0.4). Those two machines are connected to each other with Gigabit ethernet. The raid-z volume is divided into three parts: two zvols, shared with iscsi, and one directly on top of zfs, shared with nfs and similar. I ssh'd into the freeNAS box, and did some testing on the disks. I used ddto test the third part of the disks (straight on top of ZFS). I copied a 4GB (2x the amount of RAM) block from /dev/zero to the disk, and the speed was 80MB/s. Other of the iSCSI shared zvols is a datastore for the ESXi. I did similar test with time dd .. there. Since the dd there did not give the speed, I divided the amount of data transfered by the time show by time. The result was around 30-40 MB/s. Thats about half of the speed from the freeNAS host! Then I tested the IO on a VM running on the same ESXi host. The VM was a light CentOS 6.0 machine, which was not really doing anything else at that time. There were no other VMs running on the server at the time, and the other two "parts" of the disk array were not used. A similar dd test gave me result of about 15-20 MB/s. That is again about half of the result on a lower level! Of course the is some overhead in raid-z - zfs - zvolume - iSCSI - VMFS - VM, but I don't expect it to be that big. I belive there must be something wrong in my system. I have heard about bad performance of freeNAS's iSCSI, is that it? I have not managed to get any other "big" SAN OS to run on the box (NexentaSTOR, openfiler). Can you see any obvious problems with my setup?

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  • What do you upgrade to make games load faster? [on hold]

    - by Superbest
    Let's say you have a relatively modern game like Shogun 2. The loading screens take several minutes. This bothers you and you'd like to improve it. What is actually going on when loading screens are up? I'm guessing assets are being loaded into memory from disk, and possibly being decompressed first. However, what is actually causing the slow down? The memory? Mainboard? CPU? HDD? If you had $100 to spend on upgrades and your only goal is to speed up loading screens without reducing other performance, what component of the computer does it make sense to upgrade for maximum benefit? If your answer is "it depends on the existing setup", what sort of benchmarks would you run to determine what is causing the bottleneck? What if you had $500 instead? I give the two budgets for context. I am not asking for actual recommendations about which component to buy (nor are the numbers supposed to be rigid limits), but what features are important when shopping for components with small and large budgets (a large budget could allow buying multiple components which are not so good on their own, but work particularly well together). I mention Shogun 2 as an example, but I'm asking about reducing overall loading times, across all games, not just one game. Therefore, "put it on a solid state disk" probably won't be good solution, because putting every game on your SDD will quickly fill it up.

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  • Does AMD Cool n Quiet Slow Down Your System?

    - by Software Monkey
    I discovered today that having AMD Cool n Quiet enabled in my BIOS appears to be slowing down my Windows XP SP2 system by about 29% on memory & CPU intensive workloads. I was wondering if (a) anyone else had encountered this, (b) anyone can offer an explanation, (c) there are any negatives I need to be aware of if I keep AMD CnQ disabled. With some superficial testing so far, I don't immediately notice any difference with CnQ off (other than the performance being what I expected from this new hardware). It seems to ramp up the CPU fan a little bit as my program maxes out 1 core, but that's the same as with CnQ on. And when I let the system idle the CPU fan slows down and the systems as quiet as a mouse (after years of 6 small fans churning like they want to go into orbit it's nice to again have a system where I can hear the HDDs seeking). Bonus question: Does CnQ cause issues with system stability? I ask because the reason I disabled it was because I have had a few freezes and 1 spontaneous reboot with my new hardware.

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  • Win 2008 R2 - copying TO disk is very slow, copying FROM is more or less okay

    - by avs099
    I have Windows 2008 R2 SP1 with 4 identical SATA disks (Seagate Barracude 7200) in RAID 5 array. It has 4Gb of memory; all recent updates are installed. Problem: when I copy large file from one folder to another, I get about 10MB/s average speed. When I read this file from network share via 1Gbps connection - I get about 25-30 MB/s. Both numbers seems to be low for me - but specifically I'm very frustrated with low write speed. there is no antivirus, no hyper-v, it's just a fileserver - i when i do my tests nobody else reads/write from it (we have only 4 people in a team, so I'm sure). Not sure if that matters, but there is only 1 logic disk "C" with all available space (1400 GB). I'm not an admin at all, so I have no idea where to look and what other information to provide. I did run performance monitor with "% idle time", "avg bytes read", "avg byte write" - here is the screenshot: I'm not sure why there are such obvious spikes. Any idea? Please let me know if you need me to provide more information - what counters should I check, etc. I'm very eager to get this solved. Thank you. UPDATE: we have another Windows 2008 R2 SP1 server with 2 RAID1 arrays - one is disk C (where windows is installed, another one is disk E). It is running Hyper-V and does not have antivirus. I noticed the following behavior when I copy large file (few GBs): C - C: about 50MB/sec C - E: about 55MB/sec E - E: 8MB/sec!!! E - C: 8MB/sec!!! what could cause this?? E drive is RAID1 array from same Seagate Barracuda 1TB drives..

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  • virtual disk image - file or partition

    - by tylerl
    I'm looking at the differences between using a file versus a partition to store a virtual disk image in VM use. The common knowledge is that partition-based images are faster than file-based images because of a decreased overhead. It makes sense, but I've never seen any actual numbers. My own testing bears out a different result. When I benchmark a direct-to-partition virtual disk, then format that same partition with ext4, create a virtual disk image stored on that ext4 filesystem, and then benchmark that, I see no speedup at all for the direct-to-partition virtual disk. Instead on some systems the file-based image is even faster (possibly due to host OS caching or something like that). This test was repeated many times on many systems, with fairly consistent results. So perhaps throwing out the performance justification, is it still considered better to use a partition rather than a virtual disk image? Is there some other reason why direct partition access is better than image files? Or perhaps is there some reason to go the other way around? Perhaps an advantage in one of the virtual disk file formats that you don't get with raw partition images?

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  • Server nearly unusable when doing disk writes

    - by Wikser
    My question closely relates to my last question here on serverfault. I was copying about 5GB from a 10 year old desktop computer to the server. The copy was done in Windows Explorer. In this situation I would assume the server to be bored by the dataflow. But as usual with this server, it really slowed down. At least I could work with the remote session, even there was some serious latency. The copy took its time (20min?). In this time I went to a colleague and he tried to log in in the same server via remote desktop (for some other reason). It took about a minute to get to the login screen, a minute to open the control panel, a minute to open the performance monitor, ... Icons were loading maybe one per second. We saw the following (from memory): CPU: 2% Avg. Queue Length: 50 Pages/sec: 115 (?) There was no other considerable activity on the server. The server seldom serves some ASP.NET pages, which became also very slow in this time. The relevant configuration is as follows: Windows 2003 SEAGATE ST3500631NS (7200 rpm, 500 GB) LSI MegaRAID based RAID 5 4 disks, 1 hot spare Write Through No read-ahead Direct Cache Mode Harddisk-Cache-Mode: off Is this normal behaviour for such a configuration? What measurements could give further clues? Is it reasonable to reduce the priority of such copy I/O and favour other processes like the remote desktop? How would you do that? Many thanks!

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