Re: [PATCH v3 06/14] sched/cpufreq: uclamp: add utilization clamping for RT tasks
From: Juri Lelli <juri.lelli@redhat.com>
Date: 2018-08-07 13:26:42
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Hi, On 06/08/18 17:39, Patrick Bellasi wrote: [...]
quoted hunk ↗ jump to hunk
@@ -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.
*/
- 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);
+ }Best, - Juri