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    Subject[PATCH -mm] i386: cpu_relax() smp.c (was: [RFC -mm] more cpu_relax() places?)
    Hi,

    On Mon, Jun 12, 2006 at 08:37:43PM +0200, Andreas Mohr wrote:
    > Hi all,
    >
    > while reviewing 2.6.17-rc6-mm1, I found some places that might
    > want to make use of cpu_relax() in order to not block secondary
    > pipelines while busy-polling (probably especially useful on SMT CPUs):

    OK, no replies arguing against anything, thus patch follow-up. ;)
    (no. 1 of 3)

    Signed-off-by: Andreas Mohr <andi@lisas.de>


    diff -urN linux-2.6.17-rc6-mm2.orig/arch/i386/kernel/smp.c linux-2.6.17-rc6-mm2.my/arch/i386/kernel/smp.c
    --- linux-2.6.17-rc6-mm2.orig/arch/i386/kernel/smp.c 2006-06-08 10:38:04.000000000 +0200
    +++ linux-2.6.17-rc6-mm2.my/arch/i386/kernel/smp.c 2006-06-13 19:33:22.000000000 +0200
    @@ -388,9 +388,11 @@
    */
    send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR);

    - while (!cpus_empty(flush_cpumask))
    + while (!cpus_empty(flush_cpumask)) {
    + cpu_relax();
    /* nothing. lockup detection does not belong here */
    mb();
    + }

    flush_mm = NULL;
    flush_va = 0;
    -
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