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    SubjectRe: [PATCH 0/3] cpufreq: Replace timers with utilization update callbacks
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    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.

    thanks,
    Steve

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