Messages in this thread |  | | Date | Thu, 9 Apr 2015 10:58:59 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] hrtimer: Replace cpu_base->active_bases with a direct check of the active list |
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On Thu, Apr 09, 2015 at 09:20:39AM +0200, Ingo Molnar wrote: > 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; > > so in practice we not only touch every cacheline in every timer > interrupt, but we _dirty_ them, even the inactive ones. >
Urgh we should really _really_ kill that entire softirq mess.
All it needs it hrtimer_start*() returning -ENOTIME when it cannot queue the timer.
Of course, all that needs it auditing all hrtimer_start*() callsites, which is a lot of work.
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