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Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig
Date 2015-09-08 14:30 +0200
Message-ID <q6qca-48n-43@gated-at.bofh.it> (permalink)
References (2 earlier) <q4MAa-1Sc-5@gated-at.bofh.it> <q66Gt-1eb-9@gated-at.bofh.it> <q67sU-2ob-39@gated-at.bofh.it> <q69O1-5Bh-5@gated-at.bofh.it> <q6lvQ-5SG-21@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Tue, Sep 08, 2015 at 09:22:05AM +0200, Vincent Guittot wrote:
> No, but
> sa->util_avg = (sa->util_sum << SCHED_CAPACITY_SHIFT) / LOAD_AVG_MAX;
> will fix the unit issue.

Tricky that, LOAD_AVG_MAX very much relies on the unit being 1<<10.

And where load_sum already gets a factor 1024 from the weight
multiplication, util_sum does not get such a factor, and all the scaling
we do on it loose bits.

So at the moment we go compute the util_avg value, we need to inflate
util_sum with an extra factor 1024 in order to make it work.

And seeing that we do the shift up on sa->util_sum without consideration
of overflow, would it not make sense to add that factor before the
scaling and into the addition?

Now, given all that, units are a complete mess here, and I'd not mind
something like:

#if (SCHED_LOAD_SHIFT - SCHED_LOAD_RESOLUTION) != SCHED_CAPACITY_SHIFT
#error "something usefull"
#endif

somewhere near here.


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Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-07 17:40 +0200
  Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-07 18:30 +0200
    Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-07 21:00 +0200
      Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-07 21:50 +0200
        Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-08 14:50 +0200
      Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 09:30 +0200
        Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 14:30 +0200
          Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 15:00 +0200
            Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 16:10 +0200
              Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-08 16:40 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 16:50 +0200
            Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-08 16:30 +0200
              Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 17:40 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-10 00:30 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-10 13:10 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-10 13:20 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-10 14:10 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-11 10:40 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-10 19:30 +0200
              Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-08 18:50 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-09 11:50 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-09 11:50 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-09 13:10 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-11 19:20 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-17 12:00 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-17 12:50 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-21 11:10 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-21 19:40 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-22 09:30 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Leo Yan <leo.yan@linaro.org> - 2015-09-11 09:50 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-11 12:00 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Leo Yan <leo.yan@linaro.org> - 2015-09-11 16:20 +0200
            Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-10 05:00 +0200
              Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-10 12:10 +0200
          Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 15:50 +0200
            Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 16:20 +0200
              Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 17:20 +0200
        Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-08 15:00 +0200
          Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 16:10 +0200
            Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-08 16:30 +0200
          Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-10 06:10 +0200
            Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-10 12:10 +0200
              Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-11 10:20 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-11 12:30 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-11 19:10 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-12 04:20 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-14 19:40 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-14 15:00 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-14 19:40 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-15 08:50 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-15 19:20 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-16 04:30 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-16 19:10 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-17 12:30 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-15 10:40 +0200
                Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-16 17:50 +0200
      Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by  capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 13:50 +0200
  [tip:sched/core] sched/fair:   Get rid of scaling utilization by capacity_orig tip-bot for Dietmar Eggemann <tipbot@zytor.com> - 2015-09-13 13:10 +0200

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