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Commit b37d9316 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/fair: Rework and comment the group_capacity code 



Pull out the group_capacity computation so that we can more clearly
comment its issues.

Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-az1hl1ya55k361nkeh9bj0yw@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 863bffc8

kernel/sched/fair.c

+24 −8
Original line number Original line Diff line number Diff line
@@ -4553,6 +4553,27 @@ static inline int sg_imbalanced(struct sched_group *group) 
	return group->sgp->imbalance;

	return group->sgp->imbalance;

}

}





/*

 * Compute the group capacity.

 *

 * For now the capacity is simply the number of power units in the group_power.

 * A power unit represents a full core.

 *

 * This has an issue where N*frac(smt_power) >= 1, in that case we'll see extra

 * 'cores' that aren't actually there.

 */

static inline int sg_capacity(struct lb_env *env, struct sched_group *group)

{



	unsigned int power = group->sgp->power;

	unsigned int capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE);



	if (!capacity)

		capacity = fix_small_capacity(env->sd, group);



	return capacity;

}



/**

/**

 * update_sg_lb_stats - Update sched_group's statistics for load balancing.

 * update_sg_lb_stats - Update sched_group's statistics for load balancing.

 * @env: The load balancing environment.

 * @env: The load balancing environment.
@@ -4596,16 +4617,11 @@ static inline void update_sg_lb_stats(struct lb_env *env, 
	if (sgs->sum_nr_running)

	if (sgs->sum_nr_running)

		sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;

		sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;





	sgs->group_imb = sg_imbalanced(group);



	sgs->group_capacity =

		DIV_ROUND_CLOSEST(sgs->group_power, SCHED_POWER_SCALE);



	if (!sgs->group_capacity)

		sgs->group_capacity = fix_small_capacity(env->sd, group);



	sgs->group_weight = group->group_weight;

	sgs->group_weight = group->group_weight;





	sgs->group_imb = sg_imbalanced(group);

	sgs->group_capacity = sg_capacity(env, group);



	if (sgs->group_capacity > sgs->sum_nr_running)

	if (sgs->group_capacity > sgs->sum_nr_running)

		sgs->group_has_capacity = 1;

		sgs->group_has_capacity = 1;

}

}