Date: Sun, 28 Jun 2009 15:44:47 -0500 From: Dan Nelson <dnelson@allantgroup.com> To: msnkipa@mail.ru Cc: freebsd-hackers@freebsd.org Subject: Re: Can I bind POSIX thread to cpu core? Message-ID: <20090628204446.GI76275@dan.emsphone.com> In-Reply-To: <E1MKyyu-0002jv-00.msnkipa-mail-ru@f103.mail.ru> References: <E1MKyyu-0002jv-00.msnkipa-mail-ru@f103.mail.ru>
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In the last episode (Jun 28):
> I have system with 4 core cpu. How can I bind POSIX thread to the one
> core? I mean that this thread can be executed on the fixed core.
See the cpuset(2) and cpuset_setaffinity(2) manpages. Something like this
should work:
#include <err.h>
#include <stdio.h>
#include <sys/param.h>
#include <sys/cpuset.h>
int main(void)
{
int i;
cpuset_t myset;
/* Get CPU mask for the current thread */
if (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, sizeof(myset), &myset) == -1)
err(1, "getaffinity failed");
/* Find first available CPU - don't assume CPU0 is always available */
for (i = 0; i < CPU_SETSIZE; i++)
if (CPU_ISSET(i, &myset))
break;
if (i == CPU_SETSIZE)
err(1, "Not allowed to run on any CPUs? How did I print this, then?");
/* Set new CPU mask */
printf ("Setting affinity to CPU %d\n", i);
CPU_ZERO(&myset);
CPU_SET(i, &myset);
if (cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, sizeof(myset), &myset) == -1)
warn("setaffinity failed");
/* Do CPU-intensive stuff here */
return 0;
}
--
Dan Nelson
dnelson@allantgroup.com
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