Re: Question about setting affinity in 2.4

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Willy,

Thanks for the heads up and patch location.  It looks like the guys at
RH seemed to have applied a patch to allow one to set affinity,
however, it might be that it is broken.  Guess I will have to contact
the RH people to get an update as to what they did/did not do.

Thanks!
Phy

On 2/18/07, Willy Tarreau <[email protected]> wrote:
Hi Phy !

On Sun, Feb 18, 2007 at 06:02:17PM -0800, Phy Prabab wrote:
> Hello everyone,
>
> I am trying to set affinity on a program to make sure I can get the
> best use of the cache as possible and to eliminate as much noise as
> possible with running my program.  I have tried unsuccessfully to set
> affinity using sched_set/getaffinity and the CPU_SET macros.  In
> particular, I can not seem to get the process to use affinity I
> specify as in:
>
> int main () {
>  cpu_set_t mask;
>  cpu_set_t setmask;
>  long long x;
>  double foo;
>  printf("Mask set to %08lx\n", sched_getaffinity(0, &mask));
>  CPU_SET(1, &mask);
>  if (sched_setaffinity(0, &mask) == -1) {
>     printf("error setting affinity.");
>  }
>
>  printf("Mask is reset to %08lx\n", sched_getaffinity(0, &mask));
>  // do some long lasting calculations ....
>
>  return;
> }
>
> No mater what I do, the process is never bond to the processor in
> question as exposed by this little appy and by cat /proc/<pid>/cpu.
> Is this just impossible to do?
>
> Ah, the kernel I am using is RH 2.4.21-37.ELsmp.

I don't know for RH kernel, but the affinity syscalls are not in 2.4
mainline. You can apply the patch without much hassle if you want. It's
in Robert Love's directory :

 http://www.kernel.org/pub/linux/kernel/people/rml/cpu-affinity/v2.4/

I believe you'll have to use an -ac patch for RHEL.

> TIA!
> Phy

regards,
Willy


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux