Messages in this thread | | | Date | Wed, 30 May 2018 10:51:43 +0200 | From | Juri Lelli <> | Subject | Re: [PATCH v5 05/10] cpufreq/schedutil: get max utilization |
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On 30/05/18 09:37, Quentin Perret wrote: > On Tuesday 29 May 2018 at 11:52:03 (+0200), Juri Lelli wrote: > > On 29/05/18 09:40, Quentin Perret wrote: > > > Hi Vincent, > > > > > > On Friday 25 May 2018 at 15:12:26 (+0200), Vincent Guittot wrote: > > > > Now that we have both the dl class bandwidth requirement and the dl class > > > > utilization, we can use the max of the 2 values when agregating the > > > > utilization of the CPU. > > > > > > > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > > > > --- > > > > kernel/sched/sched.h | 6 +++++- > > > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > > > > index 4526ba6..0eb07a8 100644 > > > > --- a/kernel/sched/sched.h > > > > +++ b/kernel/sched/sched.h > > > > @@ -2194,7 +2194,11 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {} > > > > #ifdef CONFIG_CPU_FREQ_GOV_SCHEDUTIL > > > > static inline unsigned long cpu_util_dl(struct rq *rq) > > > > { > > > > - return (rq->dl.running_bw * SCHED_CAPACITY_SCALE) >> BW_SHIFT; > > > > + unsigned long util = (rq->dl.running_bw * SCHED_CAPACITY_SCALE) >> BW_SHIFT; > > > > + > > > > + util = max_t(unsigned long, util, READ_ONCE(rq->avg_dl.util_avg)); > > > > > > Would it make sense to use a UTIL_EST version of that signal here ? I > > > don't think that would make sense for the RT class with your patch-set > > > since you only really use the blocked part of the signal for RT IIUC, > > > but would that work for DL ? > > > > Well, UTIL_EST for DL looks pretty much what we already do by computing > > utilization based on dl.running_bw. That's why I was thinking of using > > that as a starting point for dl.util_avg decay phase. > > Hmmm I see your point, but running_bw and the util_avg are fundamentally > different ... I mean, the util_avg doesn't know about the period, which is > an issue in itself I guess ... > > If you have a long running DL task (say 100ms runtime) with a long period > (say 1s), the running_bw should represent ~1/10 of the CPU capacity, but > the util_avg can go quite high, which means that you might end up > executing this task at max OPP. So if we really want to drive OPPs like > that for deadline, a util_est-like version of this util_avg signal > should help. Now, you can also argue that going to max OPP for a task > that _we know_ uses 1/10 of the CPU capacity isn't right ...
Yep, that's my point. :)
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