Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Mon, 21 Aug 2023 12:34:06 +0200 | Subject | Re: [PATCH 0/4] Fix dvfs_headroom escaping uclamp constraints |
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On Sun, Aug 20, 2023 at 11:08 PM Qais Yousef <qyousef@layalina.io> wrote: > > DVFS headroom, or map_util_perf(), is applied after uclamp restrictions are > applied in effective_cpu_util(). This will lead to two problems for uclamp: > > 1. If util < uclamp_min, we'll run faster than uclamp_min. For example > util = 50, uclamp_min = 100. map_util_perf() = 125 instead of 100. > > 2. If util > uclamp_max, we'll run faster than uclamp_max. For example > util = 900, uclamp_max = 800, map_util_perf() = 1000. > > First patch rename the function to apply_dvfs_headroom() to reflect what it > really does. It is not really mapping util, but provides some headroom for the > util to grow. Provide a documentation for the function too. > > Second patch is the actual fix. > > Third patch moves apply_dvfs_headroom() to sched.h as there are no longer > users outside the scheduler. > > Fourth patch is an RFC to redefine what the headroom means for RT, DL and IRQ > pressures. > > Thanks!
For the first 3 patches in the series
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
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