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Commit f1ec666a authored by Chris Redpath's avatar Chris Redpath
Browse files

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>

Change-Id: I4b3d79141fc8e53dc51cd63ac11096c2e3cb10f5
Signed-off-by: default avatarChris Redpath <chris.redpath@arm.com>
parent 58afaac0

include/linux/sched/sysctl.h

+1 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 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_wakeup_granularity;

extern unsigned int sysctl_sched_child_runs_first;

kernel/sched/fair.c

+15 −2
Original line number Diff line number Diff line
@@ -54,6 +54,11 @@ 
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;



/*

 * The initial- and re-scaling of tunables is configurable

 *
@@ -6343,13 +6348,21 @@ static bool cpu_overutilized(int cpu) 
	return (capacity_of(cpu) * 1024) < (cpu_util(cpu) * capacity_margin);

}



static int select_energy_cpu_brute(struct task_struct *p, int prev_cpu)

static int select_energy_cpu_brute(struct task_struct *p, int prev_cpu, int sync)

{

	int i;

	int min_diff = 0, energy_cpu = prev_cpu, spare_cpu = prev_cpu;

	unsigned long max_spare = 0;

	struct sched_domain *sd;



	if (sysctl_sched_sync_hint_enable && sync) {

		int cpu = smp_processor_id();



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

			return cpu;

		}

	}



	sd = rcu_dereference(per_cpu(sd_ea, prev_cpu));



	if (!sd)
@@ -6427,7 +6440,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f 
	rcu_read_lock();

	sd = rcu_dereference(cpu_rq(prev_cpu)->sd);

	if (energy_aware() && sd && !sd_overutilized(sd)) {

		new_cpu = select_energy_cpu_brute(p, prev_cpu);

		new_cpu = select_energy_cpu_brute(p, prev_cpu, sync);

		goto unlock;

	}

kernel/sysctl.c

+7 −0
Original line number Diff line number Diff line
@@ -329,6 +329,13 @@ 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,