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| author | Quentin Perret <quentin.perret@arm.com> | 2018-05-24 17:35:02 +0100 |
|---|---|---|
| committer | Amit Pundir <amit.pundir@linaro.org> | 2018-10-08 10:20:23 +0530 |
| commit | b582687429b6281d7c63d7b5e89e143e55415a8c (patch) | |
| tree | f84133b4bca481d0de91d7b28c2236257545c5ff | |
| parent | 6a3f85fa2f511ba86a17eb61c286282bee554b0a (diff) | |
| download | linaro-android-b582687429b6281d7c63d7b5e89e143e55415a8c.tar.gz | |
ANDROID: sched/fair: Bypass energy computation for prefer_idle tasks
If the only pre-selected candidate CPU in find_energy_efficient_cpu()
happens to be prev_cpu, there is not point in computing the system
energy since we have nothing to compare it against, so we currently bail
out early. The same logic can be extended when prefer_idle tasks are
routed in the energy-aware wake-up path: if the only candidate is idle
for a prefer_idle task, just select it no matter what the energy impact
is. That should help speeding-up wake-ups of prefer_idle tasks, at least
when find_best_target() is used for them.
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Change-Id: Idd0e387e4a766061cc05d2584df3a31e4dabfd09
| -rw-r--r-- | kernel/sched/fair.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 95d4a3beea1c..2384841c5ceb 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6969,11 +6969,17 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu, else select_max_spare_cap_cpus(sd, candidates, pd, p); - /* Bail out if there is no candidate, or if the only one is prev_cpu */ + /* Bail out if no candidate was found. */ weight = cpumask_weight(candidates); - if (!weight || (weight == 1 && cpumask_first(candidates) == prev_cpu)) + if (!weight) return prev_cpu; + /* If there is only one sensible candidate, select it now. */ + cpu = cpumask_first(candidates); + if (weight == 1 && ((schedtune_prefer_idle(p) && idle_cpu(cpu)) || + (cpu == prev_cpu))) + return cpu; + if (cpumask_test_cpu(prev_cpu, &p->cpus_allowed)) prev_energy = best_energy = compute_energy(p, prev_cpu, pd); else |