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Commit b2133c8b authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched: tidy up and simplify the bonus balance 



make the bonus balance more consistent: do not hand out a bonus if
there's too much in flight already, and only deduct as much from a
runner as it has the capacity. This makes the bonus engine a zero-sum
game (as intended).

this also simplifies the code:

   text    data     bss     dec     hex filename
  34770    2998      24   37792    93a0 sched.o.before
  34749    2998      24   37771    938b sched.o.after

and it also avoids overscheduling in sleep-happy workloads like
hackbench.c.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 98fbc798

kernel/sched_fair.c

+10 −4
Original line number Diff line number Diff line
@@ -306,6 +306,8 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr) 
		delta = min(cfs_rq->sleeper_bonus, (u64)delta_exec);

		delta = calc_delta_mine(delta, curr->load.weight, lw);

		delta = min((u64)delta, cfs_rq->sleeper_bonus);

		delta = min(delta, (unsigned long)(

			(long)sysctl_sched_runtime_limit - curr->wait_runtime));

		cfs_rq->sleeper_bonus -= delta;

		delta_mine -= delta;

	}
@@ -493,6 +495,13 @@ static void __enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) 
	unsigned long load = cfs_rq->load.weight, delta_fair;

	long prev_runtime;



	/*

	 * Do not boost sleepers if there's too much bonus 'in flight'

	 * already:

	 */

	if (unlikely(cfs_rq->sleeper_bonus > sysctl_sched_runtime_limit))

		return;



	if (sysctl_sched_features & SCHED_FEAT_SLEEPER_LOAD_AVG)

		load = rq_of(cfs_rq)->cpu_load[2];
@@ -512,16 +521,13 @@ static void __enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) 


	prev_runtime = se->wait_runtime;

	__add_wait_runtime(cfs_rq, se, delta_fair);

	schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);

	delta_fair = se->wait_runtime - prev_runtime;



	/*

	 * Track the amount of bonus we've given to sleepers:

	 */

	cfs_rq->sleeper_bonus += delta_fair;

	if (unlikely(cfs_rq->sleeper_bonus > sysctl_sched_runtime_limit))

		cfs_rq->sleeper_bonus = sysctl_sched_runtime_limit;



	schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);

}



static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)