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Subject[RFD PATCH 2/5] sched/deadline: move cpu frequency selection triggering points
Date
Since SCHED_DEADLINE doesn't track utilization signal (but reserves a
fraction of CPU bandwidth to tasks admitted to the system), there is no
point in evaluating frequency changes during each tick event.

Move frequency selection triggering points to where running_bw changes.

Co-authored-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
---
kernel/sched/deadline.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 55471016d73c..5c1a205e830f 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -52,6 +52,8 @@ void add_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
dl_rq->running_bw += dl_bw;
SCHED_WARN_ON(dl_rq->running_bw < old); /* overflow */
SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
+ /* kick cpufreq (see the comment in kernel/sched/sched.h). */
+ cpufreq_update_this_cpu(rq_of_dl_rq(dl_rq), SCHED_CPUFREQ_DL);
}

static inline
@@ -64,6 +66,8 @@ void sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
SCHED_WARN_ON(dl_rq->running_bw > old); /* underflow */
if (dl_rq->running_bw > old)
dl_rq->running_bw = 0;
+ /* kick cpufreq (see the comment in kernel/sched/sched.h). */
+ cpufreq_update_this_cpu(rq_of_dl_rq(dl_rq), SCHED_CPUFREQ_DL);
}

static inline
@@ -953,9 +957,6 @@ static void update_curr_dl(struct rq *rq)
return;
}

- /* kick cpufreq (see the comment in kernel/sched/sched.h). */
- cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_DL);
-
schedstat_set(curr->se.statistics.exec_max,
max(curr->se.statistics.exec_max, delta_exec));

--
2.10.0
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