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    SubjectRe: [PATCH 0/3] cpufreq: Replace timers with utilization update callbacks
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    On 02/09/2016 07:09 PM, Rafael J. Wysocki wrote:
    >>> >> I think additional hooks such as enqueue/dequeue would be needed in
    >>> >> RT/DL. The task tick callbacks will only run if a task in that class is
    >>> >> executing at the time of the tick. There could be intermittent RT/DL
    >>> >> task activity in a frequency domain (the only task activity there, no
    >>> >> CFS tasks) that doesn't happen to overlap the tick. Worst case the task
    >>> >> activity could be periodic in such a way that it never overlaps the tick
    >>> >> and the update is never made.
    >> >
    >> > So if I'm reading this correctly, it would be better to put the hooks
    >> > into update_curr_rt/dl()?

    That should AFAICS be sufficient to avoid stalling. It may be more than
    is required as that covers more than just enqueue/dequeue but I'm not
    sure offhand.

    >
    > 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.

    thanks,
    Steve

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