From 39b1235433aa62ce0263c265cb936531ed38d079 Mon Sep 17 00:00:00 2001 From: "lakkyung.jung" Date: Mon, 16 Apr 2018 11:23:13 +0900 Subject: [PATCH] sched/cpufreq_schedutil: use util_est for OPP selection - backport util-est from linux-power.git When schedutil looks at the CPU utilization, the current PELT value for that CPU is returned straight away. In certain scenarios this can have undesired side effects and delays on frequency selection. For example, since the task utilization is decayed at wakeup time, a long sleeping big task newly enqueued does not add immediately a significant contribution to the target CPU. This introduces some latency before schedutil will be able to detect the best frequency required by that task. Moreover, the PELT signal build-up time is a function of the current frequency, because of the scale invariant load tracking support. Thus, starting from a lower frequency, the utilization build-up time will increase even more and further delays the selection of the actual frequency which better serves the task requirements. In order to reduce this kind of latencies, we integrate the usage of the CPU's estimated utilization in the sugov_get_util function. This allows to properly consider the expected utilization of a CPU which, for example, has just got a big task running after a long sleep period. Ultimately this allows to select the best frequency to run a task right after its wake-up. Change-Id: Ibf98a4be222546733cbd88b9a8f2c8858319dd96 Signed-off-by: Patrick Bellasi Reviewed-by: Dietmar Eggemann Acked-by: Rafael J. Wysocki Acked-by: Viresh Kumar Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Rafael J. Wysocki Cc: Viresh Kumar Cc: Paul Turner Cc: Vincent Guittot Cc: Morten Rasmussen Cc: Dietmar Eggemann Cc: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org --- kernel/sched/sched.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index dd9c84dd6056..f5606acd5312 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1890,14 +1890,20 @@ static inline unsigned long cpu_util(int cpu) static inline unsigned long cpu_util_freq(int cpu) { - unsigned long util = cpu_rq(cpu)->cfs.avg.util_avg; + struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs; unsigned long capacity = capacity_orig_of(cpu); + unsigned long util = READ_ONCE(cfs_rq->avg.util_avg); #ifdef CONFIG_SCHED_WALT if (!walt_disabled && sysctl_sched_use_walt_cpu_util) { walt_util(util, cpu_rq(cpu)->prev_runnable_sum); } #endif + if (sched_feat(UTIL_EST)) { + util = max_t(unsigned long, util, + READ_ONCE(rq->cfs.avg.util_est.enqueued)); + } + return (util >= capacity) ? capacity : util; } -- 2.20.1