lkml.org 
[lkml]   [2007]   [Jul]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] [33/58] x86_64: Avoid too many remote cpu references due to /proc/stat
    On Thu, Jul 19, 2007 at 11:55:19AM +0200, Andi Kleen wrote:
    >
    > From: Ravikiran G Thirumalai <kiran@scalex86.org>
    > Too many remote cpu references due to /proc/stat.
    >
    > On x86_64, with newer kernel versions, kstat_irqs is a bit of a problem.
    > On every call to kstat_irqs, the process brings in per-cpu data from all
    > online cpus. Doing this for NR_IRQS, which is now 256 + 32 * NR_CPUS
    > results in (256+32*63) * 63 remote cpu references on a 64 cpu config.
    > /proc/stat is parsed by common commands like top, who etc, causing
    > lots of cacheline transfers
    >
    > This statistic seems useless. Other 'big iron' arches disable this.
    > Can we disable computing/reporting this statistic? This piece of
    > statistic is not human readable on x86_64 anymore,
    >
    > If not, can we optimize computing this statistic so as to avoid
    > too many remote references (patch to follow)

    If we disable this on x86_64 we should just kill it completely for consistency.

    > -#if !defined(CONFIG_PPC64) && !defined(CONFIG_ALPHA) && !defined(CONFIG_IA64)
    > +#if !defined(CONFIG_PPC64) && !defined(CONFIG_ALPHA) && !defined(CONFIG_IA64) \
    > + && !defined(CONFIG_X86_64)
    > for (i = 0; i < NR_IRQS; i++)
    > seq_printf(p, " %u", kstat_irqs(i));
    > #endif
    -
    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: 2007-07-19 12:37    [W:0.033 / U:0.500 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site