parallel processing - how the execution time drops sharply (more than expected) as the number of processors increase? -

-

i executing programme 5000000 times in parallel using "parallel.for" f#. average execution time per task given below.

number of active cores : execution time (microseconds)

2 : 866

4 : 424

8 : 210

12 : 140

16 : 106

24 : 76

32 : 60

provided fact,

by doubling number of cores, maximum speedup can get, should less than 2 (ideally can 2).

what can reason sharp speedup.

  • 2 * 866 = 1732
  • 4 * 424 = 1696
  • 8 * 210 = 1680
  • 12 * 140 = 1680
  • 16 * 106 = 1696
  • 24 * 76 = 1824
  • 32 * 60 = 1920

so increase parallelism, relative performance improves , begins fall. improvement possibly due amortization of overhead costs jit compilation or in algorithm manages parallelization.

the degradation degree of parallelism increases due sort of resource contention, excessive context switching, or like.


Comments

Post a Comment

Popular posts from this blog

javascript - Karma not able to start PhantomJS on Windows - Error: spawn UNKNOWN -

-
i lost "unknown" error: karma.conf.js: frameworks: ['mocha', 'should'], plugins: ['karma-mocha', 'karma-should', 'karma-phantomjs-launcher'], ... browsers: ['phantomjs'], error: 23 07 2015 14:35:37.691:warn [karma]: no captured browser, open http://localhost:9876/ 23 07 2015 14:35:37.701:info [karma]: karma v0.13.3 server started @ http://localhost:9876/ 23 07 2015 14:35:37.707:info [launcher]: starting browser phantomjs 23 07 2015 14:35:37.738:error [karma]: { [error: spawn unknown] code: 'unknown', errno: 'unknown', syscall: 'spawn' } error: spawn unknown @ exports._errnoexception (util.js:749:11) @ childprocess.spawn (child_process.js:1093:11) @ exports.spawn (child_process.js:933:9) @ object._execcommand (c:\users\jinga4x\git\mdl-sample-project\node_modules\karma\lib\launchers\process.js:63:21) @ object._start (c:\users\jinga4x\git\md
Read more

c# - Display ASPX Popup control in RowDeleteing Event (ASPX Gridview) -

-
i have aspxgridview includes new , delete button. delete button includs gv_rowdeleting event. want show aspxpopupcontrol (id="pupconfirm"). want user have confirm password delete item. tried: protected void gv_rowdeleting(object sender, devexpress.web.data.aspxdatadeletingeventargs e) { pupconfirm.showonpageload = true; } but nothing happened. please me. !!! you can create template column javascript prompt confirmation. <itemtemplate> <asp:linkbutton id="btndelete" runat="server" text="delete" commandname="delete" onclientclick="javascript:if(!confirm('are sure want delete record?')){return false;}"> </asp:linkbutton> </itemtemplate>
Read more

Nuget pack csproj using nuspec -

-
i want create nuget package contains specified in nuspec file, still version csproj. in order use token have pack like: nuget pack myproj.csproj but when adds dependencies , creates unwanted folder in nuget package. nuspec file is: <?xml version="1.0" encoding="utf-8"?> <package xmlns="http://schemas.microsoft.com/packaging/2011/08/nuspec.xsd"> <metadata> <id>test</id> <version>$version$</version> <title>test</title> <authors>test</authors> <owners>test</owners> <requirelicenseacceptance>false</requirelicenseacceptance> <description>test</description> <summary>test</summary> <releasenotes>test</releasenotes> <copyright>test</copyright> </metadata> <files> <file src="bin\debug\*.dll" target="lib\net45" /> <file s
Read more