Messages in this thread | | | Date | Wed, 24 May 2017 13:31:58 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH RFC 0/8] SCHED_DEADLINE freq/cpu invariance and OPP selection |
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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.
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