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  • MySQL performance

    - by kapil.israni
    Hi, I have this LAMP application with about 900k rows in MySQL and I am having some performance issues. Background - Apart from the LAMP stack , there's also a Java process (multi-threaded) that runs in its own JVM. So together with LAMP & java, they form the complete solution. The java process is responsible for inserts/updates and few selects as well. These inserts/updates are usually in bulk/batch, anywhere between 5-150 rows. The PHP front-end code only does SELECT's. Issue - the PHP/SELECT queries become very slow when the java process is running. When the java process is stopped, SELECT's perform alright. I mean the performance difference is huge. When the java process is running, any action performed on the php front-end results in 80% and more CPU usage for mysqld process. Any help would be appreciated. MySQL is running with default parameters & settings. Software stack - Apache - 2.2.x MySQL -5.1.37-1ubuntu5 PHP - 5.2.10 Java - 1.6.0_15 OS - Ubuntu 9.10 (karmic)

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  • Software development metrics and reporting

    - by David M
    I've had some interesting conversations recently about software development metrics, in particular how they can be used in a reasonably large organisation to help development teams work better. I know there have been Stack Overflow questions about which metrics are good to use - like this one, but my question is more about which metrics are useful to which stakeholders, and at what level of aggregation. As an example, my view is that code coverage is a useful metric in the following ways (and maybe others): For a team's own internal use when combined with other measurements. For facilitating/enabling/mentoring teams, where it might be instructive when considered on a team-by-team basis as a trend (e.g. if team A and B have coverage this month of 75 and 50, I'd be more concerned with team A than B if the previous month they'd had 80 and 40). For senior management when presented as an aggregated statistic across a number of teams or a whole department. But I don't think it's useful for senior management to see this on a team-by-team basis, as this encourages artifical attempts to bolster coverage with tests that merely exercise, rather than test, code. I'm in an organisation with a couple of levels in its management hierarchy, but where the vast majority of managers are technically minded and able (with many still getting their hands dirty). Some of the development teams are leading the way in driving towards agile development practices, but others lag, and there is now a serious mandate from the top for this to be the way the organisation works. A couple of us are starting a programme to encourage this. In this sort of an organisation, what sort of metrics do you think are useful, to whom, why, and at what level of aggregation? I don't want people to feel their performance is being assessed based on a metric that they can artificially influence; at the same time, the senior management are going to want some sort of evidence that progress is being made. What advice or caveats can you provide based on experience in your own organisations? EDIT We are definitely wanting to use metrics as a tool for organisational improvement not as a tool for individual performance measurement.

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  • jQuery performance

    - by jAndy
    Hi Folks, imagine you have to do DOM manipulation like a lot (in my case, it's kind of a dynamic list). Look at this example: var $buffer = $('<ul/>', { 'class': '.custom-example', 'css': { 'position': 'absolute', 'top': '500px' } }); $.each(pages[pindex], function(i, v){ $buffer.append(v); }); $buffer.insertAfter($root); "pages" is an array which holds LI elements as jQuery object. "$root" is an UL element What happens after this code is, both UL's are animated (scrolling) and finally, within the callback of animate this code is executed: $root.detach(); $root = $buffer; $root.css('top', '0px'); $buffer = null; This works very well, the only thing I'm pi**ed off is the performance. I do cache all DOM elements I'm laying a hand on. Without looking too deep into jQuery's source code, is there a chance that my performance issues are located there? Does jQuery use DocumentFragments to append things? If you create a new DOM element with var new = $('<div/>') it is only stored in memory at this point isnt it?

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  • WF performance with new 20,000 persisted workflow instances each month

    - by Nikola Stjelja
    Windows Workflow Foundation has a problem that is slow when doing WF instances persistace. I'm planning to do a project whose bussiness layer will be based on WF exposed WCF services. The project will have 20,000 new workflow instances created each month, each instance could take up to 2 months to finish. What I was lead to belive that given WF slownes when doing peristance my given problem would be unattainable given performance reasons. I have the following questions: Is this true? Will my performance be crap with that load(given WF persitance speed limitations) How can I solve the problem? We currently have two possible solutions: 1. Each new buisiness process request(e.g. Give me a new drivers license) will be a new WF instance, and the number of persistance operations will be limited by forwarding all status request operations to saved state values in a separate database. 2. Have only a small amount of Workflow Instances up at any give time, without any persistance ofso ever(only in case of system crashes etc.), by breaking each workflow stap in to a separate worklof and that workflow handling each business process request instance in the system that is at that current step(e.g. I'm submitting my driver license reques form, which is step one... we have 100 cases of that, and my step one workflow will handle every case simultaneusly). I'm very insterested in solution for that problem. If you want to discuss that problem pleas be free to mail me at [email protected]

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  • Figuring out the Nyquist performance limitation of an ADC on an example PIC microcontroller

    - by AKE
    I'm spec-ing the suitability of a dsPIC microcontroller for an analog-to-digital application. This would be preferable to using dedicated A/D chips and a separate dedicated DSP chip. To do that, I've had to run through some computations, pulling the relevant parameters from the datasheets. I'm not sure I've got it right -- would appreciate a check! (EDITED NOTE: The PIC10F220 in the example below was selected ONLY to walk through a simple example to check that I'm interpreting Tacq, Fosc, TAD, and divisor correctly in working through this sort of Nyquist analysis. The actual chips I'm considering for the design are the dsPIC33FJ128MC804 (with 16b A/D) or dsPIC30F3014 (with 12b A/D).) A simple example: PIC10F220 is the simplest possible PIC with an ADC Runs at clock speed of 8MHz. Has an instruction cycle of 0.5us (4 clock steps per instruction) So: Taking Tacq = 6.06 us (acquisition time for ADC, assume chip temp. = 50*C) [datasheet p34] Taking Fosc = 8MHz (? clock speed) Taking divisor = 4 (4 clock steps per CPU instruction) This gives TAD = 0.5us (TAD = 1/(Fosc/divisor) ) Conversion time is 13*TAD [datasheet p31] This gives conversion time 6.5us ADC duration is then 12.56 us [? Tacq + 13*TAD] Assuming at least 2 instructions for load/store: This is another 1 us [0.5 us per instruction] Which would give max sampling rate of 73.7 ksps (1/13.56) Supposing 8 more instructions for real-time processing: This is another 4 us Thus, total ADC/handling time = 17.56us (12.56us + 1us + 4us) So expected upper sampling rate is 56.9 ksps. Nyquist frequency for this sampling rate is therefore 28 kHz. If this is right, it suggests the (theoretical) performance suitability of this chip's A/D is for signals that are bandlimited to 28 kHz. Is this a correct interpretation of the information given in the data sheet in obtaining the Nyquist performance limit? Any opinions on the noise susceptibility of ADCs in PIC / dsPIC chips would be much appreciated! AKE

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  • Naming multi-instance performance counters in .NET

    - by Roger Lipscombe
    Most multiple instance performance counters in Windows seem to automatically(?) have a #n on the end if there's more than one instance with the same name. For example: if, in Perfmon, you look under the Process category, you'll see: ... dwm explorer explorer#1 ... I have two explorer.exe processes, so the second counter has #1 appended to its name. When I attempt to do this in a .NET application: I can create the category, and register the instance (using the PerformanceCounterCategory.Create that takes a CounterCreationDataCollection). I can open the counter for write and write to it. When I open the counter a second time, it opens the same counter. This means that I have two applications fighting over the counters. The documentation for PerformanceCounter.InstanceName states that # is not allowed in the name. So: how do I have multiple-instance performance counters that are actually multiple instance? And where the second (and subsequent) instances get #n appended to the name? That is: I know that I can put the process ID (e.g.) on the instance name. This works, but has the unfortunate side effect that restarting the process results in a new PID, and Perfmon continues monitoring the old counter.

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  • Improving the performance of XSL

    - by Rachel
    I am using the below XSL 2.0 code to find the ids of the text nodes that contains the list of indices that i give as input. the code works perfectly but in terms for performance it is taking a long time for huge files. Even for huge files if the index values are small then the result is quick in few ms. I am using saxon9he Java processor to execute the XSL. <xsl:variable name="insert-data" as="element(data)*"> <xsl:for-each-group select="doc($insert-file)/insert-data/data" group-by="xsd:integer(@index)"> <xsl:sort select="current-grouping-key()"/> <data index="{current-grouping-key()}" text-id="{generate-id( $main-root/descendant::text()[ sum((preceding::text(), .)/string-length(.)) ge current-grouping-key() ][1] )}"> <xsl:copy-of select="current-group()/node()"/> </data> </xsl:for-each-group> </xsl:variable> In the above solution if the index value is too huge say 270962 then the time taken for the XSL to execute is 83427ms. In huge files if the index value is huge say 4605415, 4605431 it takes several minutes to execute. Seems the computation of the variable "insert-data" takes time though it is a global variable and computed only once. Should the XSL be addessed or the processor? How can i improve the performance of the XSL.

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  • APplication performance issue : SqlServer & Oracle

    - by Mahesh
    Hi, We have a applicaiton in Silverlight,WCF, NHibernate. Currently it is supporting SQL Serve and Oracle database. As it's huge data, it is running ok on SQL Sevrer. But on Oracle it is running very slow. For one functionality it takes 5 Sec to execute on SQL Server and 30 Sec on Oracle. I am not able to figure out what will be issue. Two things that i want to share with you about our database. 1) Database: contains one base table contains column of type SQLServer: [Text] Oracle: [NCLOB] 2) Our database structure is too much normalized. May be in the oracle i have used NCLOB, that is the cause of the performance. I mean i don't know the details about it.... Can anyone please let me know what will be cause? Or Which actions do i need to follw to improve the performance as equal as SqlServer.? Thanks in advance. Mahesh.

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  • Improve performance of searching JSON object with jQuery

    - by cale_b
    Please forgive me if this is answered on SO somewhere already. I've searched, and it seems as though this is a fairly specific case. Here's an example of the JSON (NOTE: this is very stripped down - this is dynamically loaded, and currently there are 126 records): var layout = { "2":[{"id":"40","attribute_id":"2","option_id":null,"design_attribute_id":"4","design_option_id":"131","width":"10","height":"10", "repeat":"0","top":"0","left":"0","bottom":"0","right":"0","use_right":"0","use_bottom":"0","apply_to_options":"0"}, {"id":"41","attribute_id":"2","option_id":"115","design_attribute_id":"4","design_option_id":"131","width":"2","height":"1", "repeat":"0","top":"0","left":"0","bottom":"4","right":"2","use_right":"0","use_bottom":"0","apply_to_options":"0"}, {"id":"44","attribute_id":"2","option_id":"118","design_attribute_id":"4","design_option_id":"131","width":"10","height":"10", "repeat":"0","top":"0","left":"0","bottom":"0","right":"0","use_right":"0","use_bottom":"0","apply_to_options":"0"}], "5":[{"id":"326","attribute_id":"5","option_id":null,"design_attribute_id":"4","design_option_id":"154","width":"5","height":"5", "repeat":"0","top":"0","left":"0","bottom":"0","right":"0","use_right":"0","use_bottom":"0","apply_to_options":"0"}] }; I need to match the right combination of values. Here's the function I currently use: function drawOption(attid, optid) { var attlayout = layout[attid]; $.each(attlayout, function(k, v) { // d_opt_id and d_opt_id are global scoped variable set elsewhere if (v.design_attribute_id == d_att_id && v.design_option_id == d_opt_id && v.attribute_id == attid && ((v.apply_to_options == 1 || (v.option_id === optid)))) { // Do stuff here } }); } The issue is that I might iterate through 10-15 layouts (unique attid's), and any given layout (attid) might have as many as 50 possibilities, which means that this loop is being run A LOT. Given the multiple criteria that have to be matched, would an AJAX call work better? (This JSON is dynamically created via PHP, so I could craft a PHP function that could possibly do this more efficently), or am I completely missing something about how to find items in a JSON object? As always, any suggestions for improving the code are welcome! EDIT: I apologize for not making this clear, but the purpose of this question is to find a way to improve the performance. The page has a lot of javascript, and this is a location where I know that performance is lower than it could be.

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  • How can I determine PerlLogHandler performance impact?

    - by Timmy
    I want to create a custom Apache2 log handler, and the template that is found on the apache site is: #file:MyApache2/LogPerUser.pm #--------------------------- package MyApache2::LogPerUser; use strict; use warnings; use Apache2::RequestRec (); use Apache2::Connection (); use Fcntl qw(:flock); use File::Spec::Functions qw(catfile); use Apache2::Const -compile => qw(OK DECLINED); sub handler { my $r = shift; my ($username) = $r->uri =~ m|^/~([^/]+)|; return Apache2::Const::DECLINED unless defined $username; my $entry = sprintf qq(%s [%s] "%s" %d %d\n), $r->connection->remote_ip, scalar(localtime), $r->uri, $r->status, $r->bytes_sent; my $log_path = catfile Apache2::ServerUtil::server_root, "logs", "$username.log"; open my $fh, ">>$log_path" or die "can't open $log_path: $!"; flock $fh, LOCK_EX; print $fh $entry; close $fh; return Apache2::Const::OK; } 1; What is the performance cost of the flocks? Is this logging process done in parallel, or in serial with the HTTP request? In parallel the performance would not matter as much, but I wouldn't want the user to wait another split second to add something like this.

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  • Performance difference in for loop condition?

    - by CSharperWithJava
    Hello all, I have a simple question that I am posing mostly for my curiousity. What are the differences between these two lines of code? (in C++) for(int i = 0; i < N, N > 0; i++) for(int i = 0; i < N && N > 0; i++) The selection of the conditions is completely arbitrary, I'm just interested in the differences between , and &&. I'm not a beginner to coding by any means, but I've never bothered with the comma operator. Are there performance/behavior differences or is it purely aesthetic? One last note, I know there are bigger performance fish to fry than a conditional operator, but I'm just curious. Indulge me. Edit Thanks for your answers. It turns out the code that prompted this question had misused the comma operator in the way I've described. I wondered what the difference was and why it wasn't a && operator, but it was just written incorrectly. I didn't think anything was wrong with it because it worked just fine. Thanks for straightening me out.

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  • MySQL Paritioning performance

    - by Imran Pathan
    Measured performance on key partitioned tables and normal tables separately. But we couldn't find any performance improvement with partitioning. Queries are pruned. Using MySQL 5.1.47 on RHEL 4. Table details: UserUsage - Will have entries for user mobile number and data usage for each date. Mobile number and Date as PRI KEY. UserProfile - Queries prev table and stores summary for each mobile number. Mobile number PRI KEY. CREATE TABLE `UserUsage` ( `Msisdn` decimal(20,0) NOT NULL, `Date` date NOT NULL, . . PRIMARY KEY USING BTREE (`Msisdn`,`Date`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 PARTITION BY KEY(Msisdn) PARTITIONS 50; CREATE TABLE `UserProfile` ( `Msisdn` decimal(20,0) NOT NULL, . . PRIMARY KEY (`Msisdn`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 PARTITION BY KEY(Msisdn) PARTITIONS 50; Second table is updated by query select and order by date in first table in a perl program, query is select * from UserUsage where Msisdn=number order by Date desc limit 7 [Process data in perl] update UserProfile values(....) where Msisdn=number explain partition for select, shows row being scanned in a particular partition only. Is something wrong with partition design or queries as partitioning is taking almost same or more time compared to normal tables?

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  • Improving File Read Performance (single file, C++, Windows)

    - by david
    I have large (hundreds of MB or more) files that I need to read blocks from using C++ on Windows. Currently the relevant functions are: errorType LargeFile::read( void* data_out, __int64 start_position, __int64 size_bytes ) const { if( !m_open ) { // return error } else { seekPosition( start_position ); DWORD bytes_read; BOOL result = ReadFile( m_file, data_out, DWORD( size_bytes ), &bytes_read, NULL ); if( size_bytes != bytes_read || result != TRUE ) { // return error } } // return no error } void LargeFile::seekPosition( __int64 position ) const { LARGE_INTEGER target; target.QuadPart = LONGLONG( position ); SetFilePointerEx( m_file, target, NULL, FILE_BEGIN ); } The performance of the above does not seem to be very good. Reads are on 4K blocks of the file. Some reads are coherent, most are not. A couple questions: Is there a good way to profile the reads? What things might improve the performance? For example, would sector-aligning the data be useful? I'm relatively new to file i/o optimization, so suggestions or pointers to articles/tutorials would be helpful.

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  • java + increasing performance and scalability

    - by varun
    Hi, below is the a code snippet, which returns the object of a class. now the object is basially comparing to some parameter in loop. my concern is what if there are thousands of objects in loop, in that case performance and scalability can be an issue. please suggest how to improve this code for performance part public Widget get(String name,int major,int minor,boolean exact) { Widget widgetToReturn = null; if(exact) { Widget w = new Widget(name, major, minor); // for loop using JDK 1.5 version for(Widget wid : set) { if((w.getName().equals(wid.getName())) && (wid.getVersion()).equals(w.getVersion())) { widgetToReturn = w; break; } } } else { Widget w = new Widget(name, major, minor); WidgetVersion widgetVersion = new WidgetVersion(major, minor); // for loop using JDK 1.5 version for(Widget wid : set) { WidgetVersion wv = wid.getVersion(); if((w.getName().equals(wid.getName())) && major == wv.getMajor() && WidgetVersion.isCompatibleAndNewer(wv, widgetVersion)) { widgetToReturn = wid; } else if((w.getName().equals(wid.getName())) && wv.equals(widgetVersion.getMajor(), widgetVersion.getMinor())) { widgetToReturn = w; } } } return widgetToReturn; }

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  • Soap 1.2 Endpoint Performance

    - by mflair2000
    I have a Client WCF Host Service SOAP 1.2 Service setup and i'm having performance issues on the SOAP Java proxy. I have no control over how the Java service is setup, aside from the endpoint config. I have the Client running Asynchronously, and the host WCF service running in Async pattern, but i see the SOAP 1.2 proxy bottlenecking and handling the requests in a Synchronous way. Can someone take a look at the auto-generated SOAP 1.2 configuration below, from the SOAP 1.2 Service wsdl? Is there a way to configure this for Async way and improve performance? Could be configured for SOAP 1.1? <?xml version="1.0"?> <configuration> <system.web> <compilation debug="true"/> </system.web> <system.serviceModel> <bindings> <customBinding> <binding name="WebserviceListenerSoap12Binding" closeTimeout="00:30:00" openTimeout="00:30:00" receiveTimeout="00:30:00" sendTimeout="00:30:00"> <textMessageEncoding maxReadPoolSize="64" maxWritePoolSize="16" messageVersion="Soap12" writeEncoding="utf-8"> <readerQuotas maxDepth="32" maxStringContentLength="20000000" maxArrayLength="20000000" maxBytesPerRead="4096" maxNameTableCharCount="16384" /> </textMessageEncoding> <httpTransport manualAddressing="false" maxBufferPoolSize="20000000" maxReceivedMessageSize="20000000" allowCookies="false" authenticationScheme="Anonymous" bypassProxyOnLocal="false" decompressionEnabled="true" hostNameComparisonMode="StrongWildcard" keepAliveEnabled="true" maxBufferSize="20000000" proxyAuthenticationScheme="Anonymous" realm="" transferMode="Buffered" unsafeConnectionNtlmAuthentication="false" useDefaultWebProxy="true" /> </binding> </customBinding> </bindings> <client> <endpoint address="http://10.18.2.117:8080/java/webservice/WebserviceListener.WebserviceListenerHttpSoap12Endpoint/" binding="customBinding" bindingConfiguration="WebserviceListenerSoap12Binding" contract="ResolveServiceReference.WebserviceListenerPortType" name="WebserviceListenerHttpSoap12Endpoint" /> </client> </system.serviceModel> </configuration>

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  • NHibernate Performance Optimization | Suggestions invited!!!

    - by user336749
    Hi, I’m facing an issue with NHibernate performance and can you please suggest me some optimizations? Below mentioned is a small summary of my application architecture I have a windows service which is listening to a messaging bus. On receiving a message the service creates an object out of which a property is the received xml snippet and saves the message to the DB (uses NH). There is a WPF UI with a readonly connection to the DB, and on refresh of the UI it displays the objects on the screen. While the UI does a refresh, it retrieves the xml and deserializes it , from which the object’s properties are derived and binded to the screen. For example assume an xml XXX is received by the service, it deserializes the xml , creates the book object and save it to the DB and a property/column is SCHEMA which contains the xml snippet. The UI while refreshed searches all book objects by ID and creates the book objects out of the xml which is being saved (yes, the xml is the constructor param). Now my issue is that the refresh takes more than 2 minutes to display say 50 book objects. I analyzed it using the NHibernate profiler, and found that the time spend within the DB is negligible, however time spent to create the entities is proportionally huge(10ms:1990 ms).I guess it’s due to the fairly huge size of xml snippet and it’s deserialization. My question is, how can I improve the performance. I dispose sessions after every refresh and is not lazy loading (please note that the time spend in DB is negligible). On every refresh it’s possible that all objects are updated by some downstream systems or maybe one of them are updated.Can I implement some sort of caching mechanism in this case? Thanks in advance for any suggestions. Regards, -Mike

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  • Socket Performance C++ Or C#

    - by modernzombie
    I have to write an application that is essentially a proxy server to handle all HTTP and HTTPS requests from our server (web browsing, etc). I know very little C++ and am very comfortable writing the application features in C#. I have experimented with the proxy from Mentalis (socket proxy) which seems to work fine for small webpages but if I go to large sites like tigerdirect.ca and browse through a couple of layers it is very slow and sometimes requests don't complete and I see broken images and javascript errors. This happens with all of our vendor sites and other content heavy sites. Mentalis uses HTTP 1.0 which I know is not as efficient but should a proxy be that slow? What is an acceptable amount of performance loss from using a proxy? Would HTTP 1.1 make a noticeable difference? Would a C++ proxy be much faster than one in C#? Is the Mentalis code just not efficient? Would I be able to use a premade C++ proxy and import the DLL to C# and still get good performance or would this project call for all C++? Sorry if these are obvious questions but I have not done network programming before.

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  • Developers: How does BitLocker affect performance?

    - by Chris
    I'm an ASP.NET / C# developer. I use VS2010 all the time. I am thinking of enabling BitLocker on my laptop to protect the contents, but I am concerned about performance degradation. Developers who use IDEs like Visual Studio are working on lots and lots of files at once. More than the usual office worker, I would think. So I was curious if there are other developers out there who develop with BitLocker enabled. How has the performance been? Is it noticeable? If so, is it bad? My laptop is a 2.53GHz Core 2 Duo with 4GB RAM and an Intel X25-M G2 SSD. It's pretty snappy but I want it to stay that way. If I hear some bad stories about BitLocker, I'll keep doing what I am doing now, which is keeping stuff RAR'ed with a password when I am not actively working on it, and then SDeleting it when I am done (but it's such a pain).

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  • Misaligned Pointer Performance

    - by Elite Mx
    Aren't misaligned pointers (in the BEST possible case) supposed to slow down performance and in the worst case crash your program (assuming the compiler was nice enough to compile your invalid c program). Well, the following code doesn't seem to have any performance differences between the aligned and misaligned versions. Why is that? /* brutality.c */ #ifdef BRUTALITY xs = (unsigned long *) ((unsigned char *) xs + 1); #endif ... /* main.c */ #include <stdio.h> #include <stdlib.h> #define size_t_max ((size_t)-1) #define max_count(var) (size_t_max / (sizeof var)) int main(int argc, char *argv[]) { unsigned long sum, *xs, *itr, *xs_end; size_t element_count = max_count(*xs) >> 4; xs = malloc(element_count * (sizeof *xs)); if(!xs) exit(1); xs_end = xs + element_count - 1; sum = 0; for(itr = xs; itr < xs_end; itr++) *itr = 0; #include "brutality.c" itr = xs; while(itr < xs_end) sum += *itr++; printf("%lu\n", sum); /* we could free the malloc-ed memory here */ /* but we are almost done */ exit(0); } Compiled and tested on two separate machines using gcc -pedantic -Wall -O0 -std=c99 main.c for i in {0..9}; do time ./a.out; done

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  • KVM guest io is much slower than host io: is that normal?

    - by Evolver
    I have a Qemu-KVM host system setup on CentOS 6.3. Four 1TB SATA HDDs working in Software RAID10. Guest CentOS 6.3 is installed on separate LVM. People say that they see guest performance almost equal to host performance, but I don't see that. My i/o tests are showing 30-70% slower performance on guest than on host system. I tried to change scheduler (set elevator=deadline on host and elevator=noop on guest), set blkio.weight to 1000 in cgroup, change io to virtio... But none of these changes gave me any significant results. This is a guest .xml config part: <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/dev/vgkvmnode/lv2'/> <target dev='vda' bus='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </disk> There are my tests: Host system: iozone test # iozone -a -i0 -i1 -i2 -s8G -r64k random random KB reclen write rewrite read reread read write 8388608 64 189930 197436 266786 267254 28644 66642 dd read test: one process and then four simultaneous processes # dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct 1073741824 bytes (1.1 GB) copied, 4.23044 s, 254 MB/s # dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct skip=1024 & dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct skip=2048 & dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct skip=3072 & dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct skip=4096 1073741824 bytes (1.1 GB) copied, 14.4528 s, 74.3 MB/s 1073741824 bytes (1.1 GB) copied, 14.562 s, 73.7 MB/s 1073741824 bytes (1.1 GB) copied, 14.6341 s, 73.4 MB/s 1073741824 bytes (1.1 GB) copied, 14.7006 s, 73.0 MB/s dd write test: one process and then four simultaneous processes # dd if=/dev/zero of=test bs=1M count=1024 oflag=direct 1073741824 bytes (1.1 GB) copied, 6.2039 s, 173 MB/s # dd if=/dev/zero of=test bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test2 bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test3 bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test4 bs=1M count=1024 oflag=direct 1073741824 bytes (1.1 GB) copied, 32.7173 s, 32.8 MB/s 1073741824 bytes (1.1 GB) copied, 32.8868 s, 32.6 MB/s 1073741824 bytes (1.1 GB) copied, 32.9097 s, 32.6 MB/s 1073741824 bytes (1.1 GB) copied, 32.9688 s, 32.6 MB/s Guest system: iozone test # iozone -a -i0 -i1 -i2 -s512M -r64k random random KB reclen write rewrite read reread read write 524288 64 93374 154596 141193 149865 21394 46264 dd read test: one process and then four simultaneous processes # dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=1024 1073741824 bytes (1.1 GB) copied, 5.04356 s, 213 MB/s # dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=1024 & dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=2048 & dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=3072 & dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=4096 1073741824 bytes (1.1 GB) copied, 24.7348 s, 43.4 MB/s 1073741824 bytes (1.1 GB) copied, 24.7378 s, 43.4 MB/s 1073741824 bytes (1.1 GB) copied, 24.7408 s, 43.4 MB/s 1073741824 bytes (1.1 GB) copied, 24.744 s, 43.4 MB/s dd write test: one process and then four simultaneous processes # dd if=/dev/zero of=test bs=1M count=1024 oflag=direct 1073741824 bytes (1.1 GB) copied, 10.415 s, 103 MB/s # dd if=/dev/zero of=test bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test2 bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test3 bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test4 bs=1M count=1024 oflag=direct 1073741824 bytes (1.1 GB) copied, 49.8874 s, 21.5 MB/s 1073741824 bytes (1.1 GB) copied, 49.8608 s, 21.5 MB/s 1073741824 bytes (1.1 GB) copied, 49.8693 s, 21.5 MB/s 1073741824 bytes (1.1 GB) copied, 49.9427 s, 21.5 MB/s I wonder is that normal situation or did I missed something?

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  • Faster code with another compiler

    - by Andrei
    I'm using the standard gcc compiler in math software development with C-language. I don't know that much about compilers or compiler options, and I was just wondering, is it possible to make faster executables using another compiler or choosing better options? The default Makefile sets options -ffast-math and -O3 and I think both of them have some impact in the overall calculation time. My software is using memory quite extensively, so I imagine some options related to memory management might do the trick? Any ideas?

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  • ssh + tinyproxy: poor performance

    - by Paul
    I am currently in China and I would like to still visit some blocked websites (facebook, youtube). I have VPS in the USA and I have installed tinyproxy on it. I log in on my VPS with SSH port-forwarding and I have configured my browser appropriately. Everything works more or less: I can surf to those websites but everything is inusually slow and sometimes data transfer stops abruptly. This probably has to do with the fact that I see some errors in my shell on the VPS like : channel 6: open failed: connect failed: Also in the log-file of tinyproxy I see some bad things: ERROR Sep 06 14:52:14 [28150]: getpeer_information: getpeername() error: Transport endpoint is not connected ERROR Sep 06 14:52:15 [28153]: writebuff: write() error "Connection reset by peer" on file descriptor 7 ERROR Sep 06 14:52:15 [28168]: readbuff: recv() error "Connection reset by peer" on file descriptor 7 ERROR Sep 06 14:52:15 [28151]: readbuff: recv() error "Connection reset by peer" on file descriptor 7 ERROR Sep 06 14:52:15 [28143]: readbuff: recv() error "Connection reset by peer" on file descriptor 7 ERROR Sep 06 14:52:17 [28147]: writebuff: write() error "Connection reset by peer" on file descriptor 7 ERROR Sep 06 14:52:23 [28137]: writebuff: write() error "Connection reset by peer" on file descriptor 7 ERROR Sep 06 14:52:26 [28168]: getpeer_information: getpeername() error: Transport endpoint is not connected ERROR Sep 06 14:52:27 [28186]: read_request_line: Client (file descriptor: 7) closed socket before read. ERROR Sep 06 14:52:31 [28160]: getpeer_information: getpeername() error: Transport endpoint is not connected

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  • Looking for home networking hardware and software advice

    - by phobos7
    Note: I originally wrote this up in a blog post. I've removed any affiliate links that I put in my original post to ensure I don't annoy anybody. I've recently moved home and I now need to go to the trouble of sorting out my home network yet again. We had Virgin broadband in Hertford but you can't get Virgin in the street we've moved to so I've had to go with O2 Broadband. Normally I prefer to use my own hardward, and previously used the DLink DIR-655 router which was great, but in this situation I am using the O2 Wirelss Box III since I only have an old Netgear DG834PN Wireless G modem router and I'd rather be using Wireless N. Anyway, the place we have moved into has only one phone point in the hallway, has the best TV point in one room and the best place to put the TV and other entertainment stuff in yet another room. So, networking the house up for Internet and TV is required. The diagram below shows the things that I'll have in my home network but there are three points where I'm not quite sure what hardware to us. Wireless Access Point/Bridge, that acts only as a wireless to wire bridge and not an AP, that links up a Media Centre/PC and a couple of consoles to the network. I'm pretty much settled on us an Acer Aspire Revo R3600 as my media PC, probably with Ubuntu or Windows and XBMC installed. Wireless Access Point/Bridge, that acts only as a wireless to wire bridge and not an AP, that links up a device that can decode and stream TV from a TV aerial across the network. The device that is connected to 2). At the moment I'm considering a HDHomeRun by SiliconDust. At the moment I'm considering either the TP LINK TL-WA701ND 150Mbps Wireless Lite N Access Point (very cheap at Amazon) or the Netgear 5 GHz Wireless-N HD Access Point/Bridge. I'd love to get some insight into what you would do in my situation. What Wireless Access Point/Bridge should I put at points 1) and 2)? What device should I choose for point 3) that can decode and stream a TV signal? Is the Acer Aspire Revo R3600 a good choice? ![alt text][6] Note 2: I've also posted this question on AVForums.

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  • Stream video from one app to another in OS X (Software video input device)

    - by Josh
    Not sure how specifically to word this... I'm wondering if there's any way to take a video stream from one application, for example VLC Media Player, and present that video stream to other applications as a video input source. For example, could I broadcast a video file from my hard disk to a website that allows video conferencing using a Flash applet? Basically, I'm looking for something like Soundflower, but for video streams. Is this possible? Tags, title, question re-wording suggestions welcomed -- I'm not sure how to properly describe this. Thanks!

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