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ANDROID: sched: Unconditionally honor sync flag for energy-aware wakeups

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Since we don't do energy-aware wakeups when we are overutilized, always
honoring sync wakeups in this state does not prevent wake-wide mechanics
overruling the flag as normal.

This patch is based upon previous work to build EAS for android products.

sync-hint code taken from commit 4a5e890ec60d
"sched/fair: add tunable to force selection at cpu granularity" written
by Juri Lelli <juri.lelli@arm.com>

Change-Id: I4b3d79141fc8e53dc51cd63ac11096c2e3cb10f5
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
(cherry-picked from commit f1ec666a62dec1083ed52fe1ddef093b84373aaf)
[ Moved the feature to find_energy_efficient_cpu() and removed the
  sysctl knob ]
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
This commit is contained in:
Chris Redpath
2019-03-27 17:15:17 +00:00
committed by Quentin Perret
parent b61876ed12
commit 79e3a4a27e
1 changed files with 8 additions and 2 deletions
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10
kernel/sched/fair.c
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@@ -6336,7 +6336,7 @@ compute_energy(struct task_struct *p, int dst_cpu, struct perf_domain *pd)
* other use-cases too. So, until someone finds a better way to solve this,
* let's keep things simple by re-using the existing slow path.
*/
static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu, int sync)
{
unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX;
struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
@@ -6350,6 +6350,12 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
if (!pd || READ_ONCE(rd->overutilized))
goto fail;
cpu = smp_processor_id();
if (sync && cpumask_test_cpu(cpu, p->cpus_ptr)) {
rcu_read_unlock();
return cpu;
}
/*
* Energy-aware wake-up happens on the lowest sched_domain starting
* from sd_asym_cpucapacity spanning over this_cpu and prev_cpu.
@@ -6461,7 +6467,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
record_wakee(p);
if (sched_energy_enabled()) {
new_cpu = find_energy_efficient_cpu(p, prev_cpu);
new_cpu = find_energy_efficient_cpu(p, prev_cpu, sync);
if (new_cpu >= 0)
return new_cpu;
new_cpu = prev_cpu;