Messages in this thread | | | Date | Wed, 10 Feb 2016 23:12:05 +0100 | Subject | Re: [PATCH 0/3] cpufreq: Replace timers with utilization update callbacks | From | "Rafael J. Wysocki" <> |
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On Wed, Feb 10, 2016 at 11:07 PM, Steve Muckle <steve.muckle@linaro.org> wrote: > On 02/10/2016 01:49 PM, Rafael J. Wysocki wrote: >>>> If done this way, I guess we may pass rq_clock_task(rq) as the time >>>> >> arg to cpufreq_update_util() from there and then the cpu_lock() call >>>> >> I've added to this prototype won't be necessary any more. >>> > >>> > Is it rq_clock_task() or rq_clock()? The former can omit irq time so may >>> > gradually fall behind wall clock time, delaying callbacks in cpufreq. >> >> What matters to us is the difference between the current time and the >> time we previously took a sample and there shouldn't be too much >> difference between the two in that respect. > > Sorry, the reference to wall clock time was unnecessary. I just meant it > can lose time, which could cause cpufreq updates to be delayed during > irq heavy periods. > >> Both are good enough IMO, but I can update the patch to use rq_clock() >> if that's preferred. > > I do believe rq_clock should be used as workloads such as heavy > networking could spend a significant portion of time in interrupts, > skewing rq_clock_task significantly, assuming I understand it correctly.
OK, I'll send an update, then.
Thanks, Rafael
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