On Thu, Jul 19, 2007 at 11:55:19AM +0200, Andi Kleen wrote: > > From: Ravikiran G Thirumalai <[EMAIL PROTECTED]> > 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 [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
