Messages in this thread Patch in this message | | | Subject | Re: [Patch v4 4/6] sched/fair: update cpu_capcity to reflect thermal pressure | From | Dietmar Eggemann <> | Date | Thu, 31 Oct 2019 16:38:21 +0100 |
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On 31.10.19 11:53, Qais Yousef wrote: > On 10/28/19 16:30, Peter Zijlstra wrote: >> On Wed, Oct 23, 2019 at 01:28:40PM +0100, Qais Yousef wrote: >>> On 10/22/19 16:34, Thara Gopinath wrote: >>>> cpu_capacity relflects the maximum available capacity of a cpu. Thermal >>>> pressure on a cpu means this maximum available capacity is reduced. This >>>> patch reduces the average thermal pressure for a cpu from its maximum >>>> available capacity so that cpu_capacity reflects the actual >>>> available capacity. >>>> >>>> Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> >>>> --- >>>> kernel/sched/fair.c | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >>>> index 4f9c2cb..be3e802 100644 >>>> --- a/kernel/sched/fair.c >>>> +++ b/kernel/sched/fair.c >>>> @@ -7727,6 +7727,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu) >>>> >>>> used = READ_ONCE(rq->avg_rt.util_avg); >>>> used += READ_ONCE(rq->avg_dl.util_avg); >>>> + used += READ_ONCE(rq->avg_thermal.load_avg); >>> >>> Maybe a naive question - but can we add util_avg with load_avg without >>> a conversion? I thought the 2 signals have different properties. >> >> Changelog of patch #1 explains, it's in that dense blob of text. >> >> But yes, you're quite right that that wants a comment here. > > Thanks for the pointer! A comment would be nice indeed. > > To make sure I got this correctly - it's because avg_thermal.load_avg > represents delta_capacity which is already a 'converted' form of load. So this > makes avg_thermal.load_avg a util_avg really. Correct? > > If I managed to get it right somehow. It'd be nice if we can do inverse > conversion on delta_capacity so that avg_thermal.{load_avg, util_avg} meaning > is consistent across the board. But I don't feel strongly about it if this gets > documented properly.
So why can't we use rq->avg_thermal.util_avg here? Since capacity is closer to util than to load?
Is it because you want to use the influence of ___update_load_sum(..., unsigned long load eq. per-cpu delta_capacity in your signal?
Why not call it this way then?
diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c index 38210691c615..d3035457483f 100644 --- a/kernel/sched/pelt.c +++ b/kernel/sched/pelt.c @@ -357,9 +357,9 @@ int update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity) { if (___update_load_sum(now, &rq->avg_thermal, capacity, - capacity, - capacity)) { - ___update_load_avg(&rq->avg_thermal, 1, 1); + 0, + 0)) { + ___update_load_avg(&rq->avg_thermal, 1, 0); return 1; }
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