Comments on: More information on pthread_setaffinity_np and sched_setaffinity http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/ A Blog on Parallel Programming and Concurrency by Michael Suess Wed, 09 Jul 2008 02:27:52 +0000 http://wordpress.org/?v=2.5 By: antx http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-64132 antx Fri, 06 Jun 2008 00:40:43 +0000 http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-64132 After inspecting my headers a week ago I found that the pthread_setaffinity_np() is located inside a #ifdef GNU or something similar, then after some googling I found that in order to link the function you MUST use -D_GNU_SOURCE, so try appending it to GCC! Luck & Happy hacking. After inspecting my headers a week ago I found that the pthread_setaffinity_np() is located inside a #ifdef GNU or something similar,
then after some googling I found that in order to link the function you MUST use -D_GNU_SOURCE, so try appending it to GCC!

Luck & Happy hacking.

]]> By: Bert Wesarg http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-6287 Bert Wesarg Wed, 11 Apr 2007 13:55:22 +0000 http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-6287 two notes: (1) pthread_setaffinity_np() is just a wrapper around sched_setaffinity() with the tid from the thread described by the pthread_t. this can be see here http://tinyurl.com/2slkve and here http://tinyurl.com/yobmfb (first note). (2) because of this, the sched_setaffinity() call can not handle the whole affinity mask of the process, so it is impossible to move a process with many threads with one sched_setaffinity() call to an other set of cpus. and the kernel does also not make a different between a process and a thread, which can be see here http://tinyurl.com/2kdu4f. two notes:

(1) pthread_setaffinity_np() is just a wrapper around sched_setaffinity() with the tid from the thread described by the pthread_t. this can be see here http://tinyurl.com/2slkve and here http://tinyurl.com/yobmfb (first note).

(2) because of this, the sched_setaffinity() call can not handle the whole affinity mask of the process, so it is impossible to move a process with many threads with one sched_setaffinity() call to an other set of cpus. and the kernel does also not make a different between a process and a thread, which can be see here http://tinyurl.com/2kdu4f.

]]> By: charles http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-3060 charles Thu, 01 Mar 2007 22:37:46 +0000 http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-3060 you have to #include "nptl/pthread.h" not pthread.h, which will probably use the linuxthreads header file which doesn't have the affinity methods. you will also need to do a -I/usr/include/nptl and -L/usr/lib/nptl. be aware you're breaking your program's compatibility with linuxthreads as a result. http://osmirrors.cerias.purdue.edu/pub/slackware/slackware-10.2/README.NPTL explains it all. you have to #include “nptl/pthread.h” not pthread.h, which will probably use the linuxthreads header file which doesn’t have the affinity methods. you will also need to do a -I/usr/include/nptl and -L/usr/lib/nptl. be aware you’re breaking your program’s compatibility with linuxthreads as a result. http://osmirrors.cerias.purdue.edu/pub/slackware/slackware-10.2/README.NPTL explains it all.

]]> By: Michael Suess http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-2673 Michael Suess Wed, 21 Feb 2007 21:48:43 +0000 http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-2673 Nils: are you sure you included pthread.h in your program? And did you link it using -lpthread? Other than that, you should have to do nothing to get it to work on Ubuntu Edgy... Nils: are you sure you included pthread.h in your program? And did you link it using -lpthread? Other than that, you should have to do nothing to get it to work on Ubuntu Edgy…

]]> By: Nils http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-2613 Nils Tue, 20 Feb 2007 22:47:02 +0000 http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-2613 I have nils@virtualdream:~$ getconf GNU_LIBPTHREAD_VERSION NPTL 2.4 But the compiler still does not know the pthread_setaffinity_np function.. any ideas? my distro is ubuntu edgy I have

nils@virtualdream:~$ getconf GNU_LIBPTHREAD_VERSION
NPTL 2.4

But the compiler still does not know the pthread_setaffinity_np function..

any ideas? my distro is ubuntu edgy

]]> By: Michael Suess http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-17 Michael Suess Mon, 21 Aug 2006 20:59:06 +0000 http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-17 Christopher, this is certainly an interesting project (and I was not aware that it existed). Nevertheless, the first thought that came to my mind when I read up on it was: "It gives a bad impression on the state of processor affinity in the Linux kernel when a project like this becomes necessary." And this is how I still feel about it... Christopher, this is certainly an interesting project (and I was not aware that it existed). Nevertheless, the first thought that came to my mind when I read up on it was: “It gives a bad impression on the state of processor affinity in the Linux kernel when a project like this becomes necessary.” And this is how I still feel about it…

]]> By: Christopher Aycock http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-16 Christopher Aycock Sat, 19 Aug 2006 09:49:05 +0000 http://www.thinkingparallel.com/2006/08/18/more-information-on-pthread_setaffinity_np-and-sched_setaffinity/#comment-16 I thought I should include a link to the Portable Linux Processor Affinity from the same team behind Open MPI: http://www.open-mpi.org/software/plpa/ They claim that this package provides a more portable, as well as more consistent, version of sched_setaffinity(). I thought I should include a link to the Portable Linux Processor Affinity from the same team behind Open MPI: http://www.open-mpi.org/software/plpa/

They claim that this package provides a more portable, as well as more consistent, version of sched_setaffinity().

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