lkml.org 
[lkml]   [2007]   [Feb]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Question about setting affinity in 2.4
    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 majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-02-19 05:43    [W:4.109 / U:0.172 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site