Commit 45de2062 authored by Alex Shi's avatar Alex Shi Committed by Ingo Molnar
Browse files

sched/fair: Rework sched_use_asym_prio() and sched_asym_prefer() 



sched_use_asym_prio() and sched_asym_prefer() are used together in various
places. Consolidate them into a single function sched_asym().

The existing sched_asym() function is only used when collecting statistics
of a scheduling group. Rename it as sched_group_asym(), and remove the
obsolete function description.

This makes the code easier to read. No functional changes.

Signed-off-by: default avatarAlex Shi <alexs@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Tested-by: default avatarRicardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: default avatarRicardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240210113924.1130448-3-alexs@kernel.org
parent 5a649837

kernel/sched/fair.c

+20 −25
Original line number Diff line number Diff line
@@ -9750,8 +9750,18 @@ static bool sched_use_asym_prio(struct sched_domain *sd, int cpu) 
	return sd->flags & SD_SHARE_CPUCAPACITY || is_core_idle(cpu);

}



static inline bool sched_asym(struct sched_domain *sd, int dst_cpu, int src_cpu)

{

	/*

	 * First check if @dst_cpu can do asym_packing load balance. Only do it

	 * if it has higher priority than @src_cpu.

	 */

	return sched_use_asym_prio(sd, dst_cpu) &&

		sched_asym_prefer(dst_cpu, src_cpu);

}



/**

 * sched_asym - Check if the destination CPU can do asym_packing load balance

 * sched_group_asym - Check if the destination CPU can do asym_packing balance

 * @env:	The load balancing environment

 * @sgs:	Load-balancing statistics of the candidate busiest group

 * @group:	The candidate busiest group
@@ -9759,34 +9769,21 @@ static bool sched_use_asym_prio(struct sched_domain *sd, int cpu) 
 * @env::dst_cpu can do asym_packing if it has higher priority than the

 * preferred CPU of @group.

 *

 * SMT is a special case. If we are balancing load between cores, @env::dst_cpu

 * can do asym_packing balance only if all its SMT siblings are idle. Also, it

 * can only do it if @group is an SMT group and has exactly on busy CPU. Larger

 * imbalances in the number of CPUS are dealt with in find_busiest_group().

 *

 * If we are balancing load within an SMT core, or at PKG domain level, always

 * proceed.

 *

 * Return: true if @env::dst_cpu can do with asym_packing load balance. False

 * otherwise.

 */

static inline bool

sched_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)

sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)

{

	/* Ensure that the whole local core is idle, if applicable. */

	if (!sched_use_asym_prio(env->sd, env->dst_cpu))

		return false;



	/*

	 * CPU priorities does not make sense for SMT cores with more than one

	 * CPU priorities do not make sense for SMT cores with more than one

	 * busy sibling.

	 */

	if (group->flags & SD_SHARE_CPUCAPACITY) {

		if (sgs->group_weight - sgs->idle_cpus != 1)

	if ((group->flags & SD_SHARE_CPUCAPACITY) &&

	    (sgs->group_weight - sgs->idle_cpus != 1))

		return false;

	}



	return sched_asym_prefer(env->dst_cpu, group->asym_prefer_cpu);

	return sched_asym(env->sd, env->dst_cpu, group->asym_prefer_cpu);

}



/* One group has more than one SMT CPU while the other group does not */
@@ -9942,7 +9939,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, 
	/* Check if dst CPU is idle and preferred to this group */

	if (!local_group && env->sd->flags & SD_ASYM_PACKING &&

	    env->idle != CPU_NOT_IDLE && sgs->sum_h_nr_running &&

	    sched_asym(env, sgs, group)) {

	    sched_group_asym(env, sgs, group)) {

		sgs->group_asym_packing = 1;

	}
@@ -11028,8 +11025,7 @@ static struct rq *find_busiest_queue(struct lb_env *env, 
		 * SMT cores with more than one busy sibling.

		 */

		if ((env->sd->flags & SD_ASYM_PACKING) &&

		    sched_use_asym_prio(env->sd, i) &&

		    sched_asym_prefer(i, env->dst_cpu) &&

		    sched_asym(env->sd, i, env->dst_cpu) &&

		    nr_running == 1)

			continue;
@@ -11899,8 +11895,7 @@ static void nohz_balancer_kick(struct rq *rq) 
		 * preferred CPU must be idle.

		 */

		for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {

			if (sched_use_asym_prio(sd, i) &&

			    sched_asym_prefer(i, cpu)) {

			if (sched_asym(sd, i, cpu)) {

				flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;

				goto unlock;

			}