Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP selection

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP selection
Date	2017-05-24 13:40 +0200
Message-ID	<tKCNX-1KT-5@gated-at.bofh.it> (permalink)
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On Wed, May 24, 2017 at 10:50:53AM +0100, Juri Lelli wrote:

> Agreed. However, problem seems to be that
> 
>  - in my opinion (current implementation) this translated into scaling
>    runtime considering current freq and cpu-max-capacity; and this is
>    required when frequency scaling is enabled and we still want to meet
>    a task's guaranteed bandwidth

Just so. The bandwidth they request is based on instructions/work. We
need to get a certain amount of instructions sorted. Nobody cares we get
an exact 10% at random frequency if they loose they finger because we
didn't get that final instruction out that stops the saw blade.

>  - Luca seemed instead to be inclined to say that, if we scale runtime
>    for !reclaim tasks, such tasks are basically allowed to run for more
>    time (when frequency is lower than max) by using some of the
>    bandwidth not allocated to themselves

Yes, that's a wrong view :-) We don't care about 'time', we care about
getting the instruction stream / work completed.

Thread

[PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP selection Juri Lelli <juri.lelli@arm.com> - 2017-05-23 11:00 +0200
  [PATCH RFC 1/8] sched/cpufreq_schedutil: make use of DEADLINE utilization signal Juri Lelli <juri.lelli@arm.com> - 2017-05-23 11:00 +0200
  [PATCH RFC 4/8] sched/cpufreq_schedutil: split utilization signals Juri Lelli <juri.lelli@arm.com> - 2017-05-23 11:00 +0200
    Re: [PATCH RFC 4/8] sched/cpufreq_schedutil: split utilization  signals Peter Zijlstra <peterz@infradead.org> - 2017-05-23 21:10 +0200
      Re: [PATCH RFC 4/8] sched/cpufreq_schedutil: split utilization  signals Juri Lelli <juri.lelli@arm.com> - 2017-05-24 11:10 +0200
    Re: [PATCH RFC 4/8] sched/cpufreq_schedutil: split utilization  signals Peter Zijlstra <peterz@infradead.org> - 2017-05-23 21:40 +0200
      Re: [PATCH RFC 4/8] sched/cpufreq_schedutil: split utilization signals "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-05-24 01:40 +0200
        Re: [PATCH RFC 4/8] sched/cpufreq_schedutil: split utilization  signals Peter Zijlstra <peterz@infradead.org> - 2017-05-24 09:10 +0200
          Re: [PATCH RFC 4/8] sched/cpufreq_schedutil: split utilization  signals Juri Lelli <juri.lelli@arm.com> - 2017-05-24 11:10 +0200
  Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP  selection Peter Zijlstra <peterz@infradead.org> - 2017-05-23 22:40 +0200
  Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP  selection Peter Zijlstra <peterz@infradead.org> - 2017-05-24 00:00 +0200
    Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP  selection Juri Lelli <juri.lelli@arm.com> - 2017-05-24 11:30 +0200
      Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP  selection Peter Zijlstra <peterz@infradead.org> - 2017-05-24 11:50 +0200
        Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP  selection Juri Lelli <juri.lelli@arm.com> - 2017-05-24 12:00 +0200
          Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP  selection Peter Zijlstra <peterz@infradead.org> - 2017-05-24 13:40 +0200
      Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP  selection Luca Abeni <luca.abeni@santannapisa.it> - 2017-05-24 12:10 +0200
        Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP  selection Peter Zijlstra <peterz@infradead.org> - 2017-05-24 13:40 +0200

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