Re: [PATCH 1/2] sched/fair: move cpufreq hook to update_cfs_rq_load_avg()
From: Dietmar Eggemann <dietmar.eggemann@arm.com>
Date: 2016-03-28 13:34:59
Also in:
lkml
Hi Steve, these patches fall into the bucket of 'optimization of updating the value only if the root cfs_rq util has changed' as discussed in '[PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util' of Mike T's current series '[PATCH 0/8] schedutil enhancements', right? I wonder if it makes sense to apply them before a proper 'capacity vote aggregation from CFS/RT/DL' has been agreed upon? Otherwise I agree with the changes in your 3 patches (inc. "[RFC PATCH] sched/fair: call cpufreq hook in additional paths") to only invoke cpufreq_update_util() if &rq->cfs.avg.util_avg has really changed. On 03/22/2016 01:21 AM, Steve Muckle wrote:
quoted hunk ↗ jump to hunk
The cpufreq hook should be called whenever the root cfs_rq utilization changes so update_cfs_rq_load_avg() is a better place for it. The current location is not invoked in the enqueue_entity() or update_blocked_averages() paths. Suggested-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Steve Muckle <redacted> --- kernel/sched/fair.c | 50 ++++++++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 24 deletions(-)diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 46d64e4ccfde..d418deb04049 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c@@ -2825,7 +2825,9 @@ static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); static inline int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) { struct sched_avg *sa = &cfs_rq->avg; + struct rq *rq = rq_of(cfs_rq); int decayed, removed = 0; + int cpu = cpu_of(rq); if (atomic_long_read(&cfs_rq->removed_load_avg)) { s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);@@ -2840,7 +2842,7 @@ static inline int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) sa->util_sum = max_t(s32, sa->util_sum - r * LOAD_AVG_MAX, 0); } - decayed = __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa, + decayed = __update_load_avg(now, cpu, sa, scale_load_down(cfs_rq->load.weight), cfs_rq->curr != NULL, cfs_rq);
Why did you change these 3 lines above? You reverted this back in "[RFC PATCH] sched/fair: call cpufreq hook in additional paths". [...]