On Thu, 9 Apr 2015, Ingo Molnar wrote:
> Plus, look at this code in hrtimer_run_queues():
>
> for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
> base = &cpu_base->clock_base[index];
> if (!base->active.next)
> continue;
>
> if (gettime) {
> hrtimer_get_softirq_time(cpu_base);
> gettime = 0;
> }
>
> if at least one base is active (on my fairly standard system all cpus
> have at least one active hrtimer base all the time - and many cpus
> have two bases active), then we run hrtimer_get_softirq_time(), which
> dirties the cachelines of all 4 clock bases:
>
> base->clock_base[HRTIMER_BASE_REALTIME].softirq_time = xtim;
> base->clock_base[HRTIMER_BASE_MONOTONIC].softirq_time = mono;
> base->clock_base[HRTIMER_BASE_BOOTTIME].softirq_time = boot;
> base->clock_base[HRTIMER_BASE_TAI].softirq_time = tai;
This is the non highres case and we actually could optimize that case
as well to avoid the cache line polution.
Thanks,
tglx
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