Messages in this thread | | | Date | Tue, 31 Jan 2023 17:36:05 +0100 | Subject | Re: [PATCH v4] sched/fair: unlink misfit task from cpu overutilized | From | Dietmar Eggemann <> |
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On 29/01/2023 17:21, Qais Yousef wrote: > On 01/26/23 12:42, Dietmar Eggemann wrote: >> On 19/01/2023 17:42, Vincent Guittot wrote:
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>> We had already this discussion whether this patch can also remove >> Capacity Inversion (CapInv). >> >> After studying the code again, I'm not so sure anymore. >> >> This patch: >> >> (1) adds a dedicated return value (-1) to util_fits_cpu() when: >> >> `util fits 80% capacity_of() && util < uclamp_min && uclamp_min > >> capacity_orig_thermal (region c)` >> >> (2) Enhancements to the CPU selection in sic() and feec() to cater for >> this new return value. > > -1 means that the task fits, but only uclamp_min hint fails. ie: the task util > is small enough to run on this cpu, but it would like to run faster and this > cpu can't satisfy this request at the moment.
Agreed.
>> IMHO this doesn't make the intention of CapInv in util_fits_cpu() >> obsolete, which is using: >> >> in CapInv: >> >> capacity_orig = capacity_orig_of() - thermal_load_avg >> capacity_orig_thermal = capacity_orig_of() - thermal_load_avg >> >> not in CapInv: >> >> capacity_orig = capacity_orig_of() >> capacity_orig_thermal = capacity_orig_of() - th_pressure >> >> Maybe I still miss a bit of the story? > > Vincent approach is different to mine. I tried to hide all the complexity in > util_fits_cpu() so all users don't care. > > But with Vincent changes, now the decision is delegated to the caller to decide > what to do if thermal pressure is causing trouble. > > IOW, I expect this line only stay after Vincent patch > > capacity_orig_thermal = capacity_orig_of() - th_pressure
OK, makes sense (for now - rework of what capacity_orig_thermal should really be still ahead of us).
Thanks!
-- Dietmar
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