Messages in this thread | | | Date | Thu, 25 Apr 2019 11:45:07 +0100 | From | Quentin Perret <> | Subject | Re: [PATCH V3 3/3] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping |
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On Tuesday 23 Apr 2019 at 18:38:46 (-0400), Thara Gopinath wrote: > I think there is one major difference between user-defined frequency > constraints and frequency constraints due to thermal events in terms of > the time period the system spends in the the constraint state. > Typically, a user constraint lasts for seconds if not minutes and I > think in this case cpu_capacity_orig should reflect this constraint and > not cpu_capacity like this patch set.
That might not always be true I think. There's tons of userspace thermal deamons out there, and I wouldn't be suprised if they were writing into the cpufreq sysfs files, although I'm not sure.
Another thing is, if you want to change the capacity_orig value, you'll need to rebuild the sched domains and all I believe. Otherwise there is a risk to 'break' the sd_asym flags. So we need to make sure we're happy to pay that price.
> Also, in case of the user > constraint, there is possibly no need to accumulate and average the > capacity constraints and instantaneous values can be directly applied to > cpu_capacity_orig. On the other hand thermal pressure is more spiky and > sometimes in the order of ms and us requiring the accumulating and > averaging. > > > > Perhaps the Intel boost stuff could be factored in there ? That is, > > at times when the boost freq is not reachable capacity_of() would appear > > smaller ... Unless this wants to be reflected instantaneously ? > Again, do you think intel boost is more applicable to be reflected in > cpu_capacity_orig and not cpu_capacity?
I'm not even sure if we want to reflect it at all TBH, but I'd be interested to see what Intel folks think :-)
Thanks, Quentin
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