Does you machine have multiple CPU's and disks? Parallel tasks on a single CPU/disk machine can only improve performance if there is significant CPU/IO overlap. A compiler is CPU and disk intensive with little CPU/IO overlap. If you don't have parallel hardware, parallel software won't improve performance.
-----Original Message----- From: Shree [mailto:[EMAIL PROTECTED] Sent: Wednesday, April 05, 2006 6:38 AM To: Ant Users List Subject: Parallel vs Sequential Hi Stefan, I tried evaluating the performance of "<parallel> task" with sequential way doing(without using <parallel>) a set of tasks. I find <parallel> does not help to improve the performance much and infact it sometimes even slower than sequential(as far I had experimented with some examples). I did several examples. One such method was - I tried compiling c files in 3 different folders(src1,src2,src3). The destination folder for the created objs were different say src1->obj1, src2->obj2, src3->obj3. I had 3 xml files, parallel.xml, sequential.xml and template.xml. Template.xml contains the logic for compiling cfiles. <!- source of template.xml --> <project name = "template" basedir="." default = "All"> <!-- the properties are passed as parameters from main build, in this case either parallel.xml or sequential.xml --> <target name = "All" depends = "create_dir"> <cc name = "msvc" outtype = "executable" objdir = "${objdir}"> <includepath path = "${includes}"/> <fileset refid = "${SrcID}"/> </cc> </target> <target name = "create_dir"> <mkdir dir = "${objdir}"/> </target> </project> Parallel.xml is the main build file that invokes the target "all" within a parallel task, so all the c-files in the 3 different folders are compiled into objs parallely while sequential is another build file that invokes the target "all" for each folders sequentially(without parallel task). I expected parallel to finish faster, but found sequential outperforming parallel most of the times. Code snippet from parallel.xml ------------------------------- <parallel> <ant antfile="template.xml" inheritrefs="true"> <property name = "SrcID" value="CSource"/> <property name = "includes" value="${env.include};${basedir}\cSource\Build"/> <property name = "objdir" value="${basedir}\Build1" /> </ant> <ant antfile="template.xml" inheritrefs="true"> <property name = "SrcID" value="CSource2"/> <property name = "includes" value="${env.include};${basedir}\cSource\Build"/> <property name = "objdir" value="${basedir}\Build2" /> </ant> <ant antfile="template.xml" inheritrefs="true"> <property name = "SrcID" value="CSource1"/> <property name = "includes" value="${env.include};${basedir}\cSource\Build"/> <property name = "objdir" value="${basedir}\Build3" /> </ant> </parallel> whereas in sequential.xml I do not use <parallel> task. Comparing the time for compiling files in sequential and parallel mode, I find using <parallel> does not improve the performance. If one argues that there are " no i/o or legitimate cpu wait/sleep" in the above code, for which - I also experimented with task that performs file i/o(Concat task) in parallel and sequential mode, still there were no results in favor of <parallel> task. What is wrong and where one should use "Parallel" tasks ? Thank you, Best regards Shreedhar --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
