Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH] [33/58] x86_64: Avoid too many remote cpu references due to /proc/stat | Date | Thu, 19 Jul 2007 12:41:28 +0200 |
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On Thursday 19 July 2007 12:21:49 Christoph Hellwig wrote: > 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.
I guess it's fine on UP only architectures. I will change it to !CONFIG_SMP unless someone complains.
-Andi
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