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ANDROID: sched/fair: ensure utilization signals are synchronized before use

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wake_cap performs task and cpu utilization synchronization which is
what allows us to subtract current task util from prev_cpu util and
have a sensible number to work with.

It looks as though if wake_wide returns 0, we could potentially not
execute wake_cap, which would result in unsynced signals we then use
for energy calculations.

This is not necessarily an issue we've seen in traces, but it looks
as though it should be changed.

Change-Id: Ic54a3cba2a10d946ea20113a04371dea04115e82
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
[Remove _wake_cap variable to match commit cf6ed9a668]
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
This commit is contained in:
Chris Redpath
2017-03-08 13:37:32 +00:00
committed by Andres Oportus
parent 7de1b8372f
commit db00ec15cb
1 changed files with 7 additions and 2 deletions
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9
kernel/sched/fair.c
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@@ -6762,8 +6762,13 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
if (sd_flag & SD_BALANCE_WAKE) {
record_wakee(p);
want_affine = (!wake_wide(p) && !wake_cap(p, cpu, prev_cpu) &&
cpumask_test_cpu(cpu, tsk_cpus_allowed(p)));
/*
* do wake_cap unconditionally as it causes task and cpu
* utilization to be synced, and we need that for energy
* aware wakeups
*/
want_affine = !wake_wide(p) && !wake_cap(p, cpu, prev_cpu)
&& cpumask_test_cpu(cpu, tsk_cpus_allowed(p));
}
if (energy_aware() && !(cpu_rq(prev_cpu)->rd->overutilized))