Re: [PATCH v6 08/16] sched/cpufreq: uclamp: Add utilization clamping for FAIR tasks
From: Peter Zijlstra <peterz@infradead.org>
Date: 2019-01-22 15:21:44
Also in:
linux-pm, lkml
On Tue, Jan 15, 2019 at 10:15:05AM +0000, Patrick Bellasi wrote:
quoted hunk ↗ jump to hunk
--- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c@@ -218,8 +218,15 @@ unsigned long schedutil_freq_util(int cpu, unsigned long util_cfs, * CFS tasks and we use the same metric to track the effective * 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 requested by currently RUNNABLE tasks. + * When there are no CFS RUNNABLE tasks, clamps are released and + * frequency will be gracefully reduced with the utilization decay. */ - util = util_cfs; + util = (type == ENERGY_UTIL) + ? util_cfs + : uclamp_util(rq, util_cfs);
That's pretty horrible; what's wrong with: util = util_cfs; if (type == FREQUENCY_UTIL) util = uclamp_util(rq, util); That should generate the same code, but is (IMO) far easier to read.
util += cpu_util_rt(rq); dl_util = cpu_util_dl(rq);