Messages in this thread | | | Date | Thu, 9 Aug 2018 16:34:23 +0100 | From | Patrick Bellasi <> | Subject | Re: [PATCH v3 06/14] sched/cpufreq: uclamp: add utilization clamping for RT tasks |
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On 07-Aug 15:26, Juri Lelli wrote: > Hi, > > On 06/08/18 17:39, Patrick Bellasi wrote: > > [...] > > > @@ -223,13 +224,25 @@ static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu) > > * utilization (PELT windows are synchronized) we can directly add them > > * to obtain the CPU's actual utilization. > > * > > - * CFS utilization can be boosted or capped, depending on utilization > > - * clamp constraints configured for currently RUNNABLE tasks. > > + * CFS and RT utilizations can be boosted or capped, depending on > > + * utilization constraints enforce by currently RUNNABLE tasks. > > + * They are individually clamped to ensure fairness across classes, > > + * meaning that CFS always gets (if possible) the (minimum) required > > + * bandwidth on top of that required by higher priority classes. > > Is this a stale comment written before UCLAMP_SCHED_CLASS was > introduced? It seems to apply to the below if branch only.
Yes, you right... I'll update the comment.
> > */ > > - util = cpu_util_cfs(rq); > > - if (util) > > - util = uclamp_util(cpu_of(rq), util); > > - util += cpu_util_rt(rq); > > + util_cfs = cpu_util_cfs(rq); > > + util_rt = cpu_util_rt(rq); > > + if (sched_feat(UCLAMP_SCHED_CLASS)) { > > + util = 0; > > + if (util_cfs) > > + util += uclamp_util(cpu_of(rq), util_cfs); > > + if (util_rt) > > + util += uclamp_util(cpu_of(rq), util_rt); > > + } else { > > + util = cpu_util_cfs(rq); > > + util += cpu_util_rt(rq); > > + util = uclamp_util(cpu_of(rq), util); > > + }
Regarding the two policies, do you have any comment?
We had an internal discussion and we found pro/cons for both... but I'm not sure keeping the sched_feat is a good solution on the long run, i.e. mainline merge ;)
-- #include <best/regards.h>
Patrick Bellasi
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