Messages in this thread | | | Date | Wed, 31 Aug 2016 16:39:07 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/2] sched: cpufreq: use rt_avg as estimate of required RT CPU capacity |
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On Fri, Aug 26, 2016 at 11:40:48AM -0700, Steve Muckle wrote: > A policy of going to fmax on any RT activity will be detrimental > for power on many platforms. Often RT accounts for only a small amount > of CPU activity so sending the CPU frequency to fmax is overkill. Worse > still, some platforms may not be able to even complete the CPU frequency > change before the RT activity has already completed. > > Cpufreq governors have not treated RT activity this way in the past so > it is not part of the expected semantics of the RT scheduling class. The > DL class offers guarantees about task completion and could be used for > this purpose.
Not entirely true. People have simply disabled cpufreq because of this.
Yes, RR/FIFO are a pain, but they should still be deterministic, and variable cpufreq destroys that.
I realize that the fmax thing is annoying, but I'm not seeing how rt_avg is much better.
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