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| author | Quentin Perret <qperret@qperret.net> | 2019-09-20 11:41:15 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-09-25 17:42:32 +0200 |
| commit | 4892f51ad54ddff2883a60b6ad4323c1f632a9d6 (patch) | |
| tree | fae92c41feea34131bc861123220f2efb33bdd6a /kernel | |
| parent | 9fc41acc89e58262c917b4be89ef00a87485804f (diff) | |
| download | linux-4892f51ad54ddff2883a60b6ad4323c1f632a9d6.tar.gz linux-4892f51ad54ddff2883a60b6ad4323c1f632a9d6.tar.bz2 linux-4892f51ad54ddff2883a60b6ad4323c1f632a9d6.zip | |
sched/fair: Avoid redundant EAS calculation
The EAS wake-up path computes the system energy for several CPU
candidates: the CPU with maximum spare capacity in each performance
domain, and the prev_cpu. However, if prev_cpu also happens to be the
CPU with maximum spare capacity in its performance domain, the energy
calculation is still done twice, unnecessarily.
Add a condition to filter out this corner case before doing the energy
calculation.
Reported-by: Pavan Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Quentin Perret <qperret@qperret.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: juri.lelli@redhat.com
Cc: morten.rasmussen@arm.com
Cc: qais.yousef@arm.com
Cc: rjw@rjwysocki.net
Cc: tkjos@google.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Fixes: eb92692b2544 ("sched/fair: Speed-up energy-aware wake-ups")
Link: https://lkml.kernel.org/r/20190920094115.GA11503@qperret.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index dfdac90fd211..83ab35e2374f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6389,7 +6389,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) } /* Evaluate the energy impact of using this CPU. */ - if (max_spare_cap_cpu >= 0) { + if (max_spare_cap_cpu >= 0 && max_spare_cap_cpu != prev_cpu) { cur_delta = compute_energy(p, max_spare_cap_cpu, pd); cur_delta -= base_energy_pd; if (cur_delta < best_delta) { |