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Commit af362094 authored by Chris Redpath's avatar Chris Redpath Committed by Quentin Perret
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ANDROID: sched: Unconditionally honor sync flag for energy-aware wakeups 



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>

Signed-off-by: default avatarChris Redpath <chris.redpath@arm.com>
(cherry-picked from commit f1ec666a62dec1083ed52fe1ddef093b84373aaf)
[ Moved the feature to find_energy_efficient_cpu() ]
Signed-off-by: default avatarQuentin Perret <quentin.perret@arm.com>
Change-Id: I4b3d79141fc8e53dc51cd63ac11096c2e3cb10f5
parent c27c5610

include/linux/sched/sysctl.h

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ enum { sysctl_hung_task_timeout_secs = 0 }; 


extern unsigned int sysctl_sched_latency;

extern unsigned int sysctl_sched_min_granularity;

extern unsigned int sysctl_sched_sync_hint_enable;

extern unsigned int sysctl_sched_cstate_aware;

extern unsigned int sysctl_sched_wakeup_granularity;

extern unsigned int sysctl_sched_child_runs_first;

kernel/sched/fair.c

+13 −2
Original line number Diff line number Diff line
@@ -40,6 +40,11 @@ 
unsigned int sysctl_sched_latency			= 6000000ULL;

unsigned int normalized_sysctl_sched_latency		= 6000000ULL;



/*

 * Enable/disable honoring sync flag in energy-aware wakeups.

 */

unsigned int sysctl_sched_sync_hint_enable = 1;



/*

 * Enable/disable using cstate knowledge in idle sibling selection

 */
@@ -6945,7 +6950,7 @@ static DEFINE_PER_CPU(cpumask_t, energy_cpus); 
 * 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_energy = ULONG_MAX, best_energy = ULONG_MAX;

	struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
@@ -6955,6 +6960,12 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) 
	struct sched_domain *sd;

	cpumask_t *candidates;



	if (sysctl_sched_sync_hint_enable && sync) {

		cpu = smp_processor_id();

		if (cpumask_test_cpu(cpu, &p->cpus_allowed))

			return cpu;

	}



	rcu_read_lock();

	pd = rcu_dereference(rd->pd);

	if (!pd || READ_ONCE(rd->overutilized))
@@ -7049,7 +7060,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f 
		record_wakee(p);



		if (static_branch_unlikely(&sched_energy_present)) {

			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;

kernel/sysctl.c

+7 −0
Original line number Diff line number Diff line
@@ -345,6 +345,13 @@ static struct ctl_table kern_table[] = { 
		.extra1		= &min_sched_granularity_ns,

		.extra2		= &max_sched_granularity_ns,

	},

	{

		.procname	= "sched_sync_hint_enable",

		.data		= &sysctl_sched_sync_hint_enable,

		.maxlen		= sizeof(unsigned int),

		.mode		= 0644,

		.proc_handler	= proc_dointvec,

	},

	{

		.procname	= "sched_wakeup_granularity_ns",

		.data		= &sysctl_sched_wakeup_granularity,