On Wed, 2007-03-28 at 03:39, Jack Steiner wrote: > This patch adds an optional method for purging the TLB on SN IA64 systems. > The change should not affect any non-SN system. > > Signed-off-by: Jack Steiner <steiner@xxxxxxx> > > --- > > +void > +smp_flush_tlb_cpumask (cpumask_t xcpumask) > +{ > + unsigned short counts[NR_CPUS]; > + cpumask_t cpumask = xcpumask; > + int count, mycpu, cpu, flush_mycpu = 0; > + > + preempt_disable(); > + mycpu = smp_processor_id(); > + > + for_each_cpu_mask(cpu, cpumask) { > + counts[cpu] = per_cpu(local_flush_count, cpu); > + mb(); > + if (cpu == mycpu) > + flush_mycpu = 1; > + else > + smp_send_local_flush_tlb(cpu); > + } > + > + if (flush_mycpu) > + smp_local_flush_tlb(); > + > + for_each_cpu_mask(cpu, cpumask) { > + count = 0; > + while(counts[cpu] == per_cpu(local_flush_count, cpu)) { Due to 64k offset of percpu data, the same percpu variable on different CPUs are very likely to be on the same cacheline of some levels of cache. So I think the operation on local_flush_count may be very cache unfriendly... Zou Nan hai - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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