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Commit f1771866 authored by Satya Durga Srinivasu Prabhala's avatar Satya Durga Srinivasu Prabhala Committed by Pavankumar Kondeti
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sched/fair: Add policy for restricting prefer_spread to newly idle balance 



Add policy for restricting prefer_spread to newly idle load balance
by expanding the tunable range.

To allow lower capacity CPUs to do aggressive newly idle load balance:
echo 3 > /proc/sys/kernel/sched_prefer_spread

To allow bother lower capacity and higher capacity CPUs to do
aggressive newly idle load balance:
echo 4 > /proc/sys/kernel/sched_prefer_spread

Change-Id: Ia62ddb29bdf592a956a9688f277178ef71dee1b3
Signed-off-by: default avatarSatya Durga Srinivasu Prabhala <satyap@codeaurora.org>
Co-developed-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
[pkondeti@codeaurora.org: The tunable range is expanded]
Signed-off-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
parent 82e942f3

kernel/sched/fair.c

+7 −5
Original line number Diff line number Diff line
@@ -4005,7 +4005,7 @@ static inline void adjust_cpus_for_packing(struct task_struct *p, 
	if (*best_idle_cpu == -1 || *target_cpu == -1)

		return;



	if (prefer_spread_on_idle(*best_idle_cpu))

	if (prefer_spread_on_idle(*best_idle_cpu, false))

		fbt_env->need_idle |= 2;



	if (task_rtg_high_prio(p) && walt_nr_rtg_high_prio(*target_cpu) > 0) {
@@ -10676,7 +10676,8 @@ static int load_balance(int this_cpu, struct rq *this_rq, 
	};



	env.prefer_spread = (idle != CPU_NOT_IDLE &&

				prefer_spread_on_idle(this_cpu) &&

				prefer_spread_on_idle(this_cpu,

				idle == CPU_NEWLY_IDLE) &&

				!((sd->flags & SD_ASYM_CPUCAPACITY) &&

				 !is_asym_cap_cpu(this_cpu)));
@@ -11202,7 +11203,8 @@ static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) 
		}

		max_cost += sd->max_newidle_lb_cost;



		if (!sd_overutilized(sd) && !prefer_spread_on_idle(cpu))

		if (!sd_overutilized(sd) && !prefer_spread_on_idle(cpu,

					idle == CPU_NEWLY_IDLE))

			continue;



		if (!(sd->flags & SD_LOAD_BALANCE))
@@ -11456,7 +11458,7 @@ static void nohz_balancer_kick(struct rq *rq) 
	 */

	if (static_branch_likely(&sched_energy_present)) {

		if (rq->nr_running >= 2 && (cpu_overutilized(cpu) ||

			prefer_spread_on_idle(cpu)))

			prefer_spread_on_idle(cpu, false)))

			flags = NOHZ_KICK_MASK;

		goto out;

	}
@@ -11827,7 +11829,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) 
	int pulled_task = 0;

	u64 curr_cost = 0;

	u64 avg_idle = this_rq->avg_idle;

	bool prefer_spread = prefer_spread_on_idle(this_cpu);

	bool prefer_spread = prefer_spread_on_idle(this_cpu, true);

	bool force_lb = (!is_min_capacity_cpu(this_cpu) &&

				silver_has_big_tasks() &&

				(atomic_read(&this_rq->nr_iowait) == 0));

kernel/sched/walt.h

+12 −7
Original line number Diff line number Diff line
@@ -451,15 +451,20 @@ static int in_sched_bug; 
	}						\

})



static inline bool prefer_spread_on_idle(int cpu)

static inline bool prefer_spread_on_idle(int cpu, bool new_ilb)

{

	if (likely(!sysctl_sched_prefer_spread))

	switch (sysctl_sched_prefer_spread) {

	case 1:

		return is_min_capacity_cpu(cpu);

	case 2:

		return true;

	case 3:

		return (new_ilb && is_min_capacity_cpu(cpu));

	case 4:

		return new_ilb;

	default:

		return false;



	if (is_min_capacity_cpu(cpu))

		return sysctl_sched_prefer_spread >= 1;



	return sysctl_sched_prefer_spread > 1;

	}

}



#else /* CONFIG_SCHED_WALT */

kernel/sysctl.c

+1 −1
Original line number Diff line number Diff line
@@ -568,7 +568,7 @@ static struct ctl_table kern_table[] = { 
		.mode		= 0644,

		.proc_handler   = proc_dointvec_minmax,

		.extra1		= &zero,

		.extra2		= &two,

		.extra2		= &four,

	},

	{

		.procname	= "walt_rtg_cfs_boost_prio",