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sched/fair: Reduce the periodic update duration 

Instead of using the cfs_rq_is_decayed() which monitors all *_avg
and *_sum, we create a cfs_rq_has_blocked() which only takes care of
util_avg and load_avg. We are only interested by these 2 values which are
decaying faster than the *_sum so we can stop the periodic update earlier.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: brendan.jackman@arm.com
Cc: dietmar.eggemann@arm.com
Cc: morten.rasmussen@foss.arm.com
Cc: valentin.schneider@arm.com
Link: http://lkml.kernel.org/r/1518517879-2280-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Vincent Guittot 2018-02-13 11:31:18 +01:00 committed by Ingo Molnar
parent f643ea2207
commit 1936c53ce8
1 changed files with 17 additions and 4 deletions
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21
kernel/sched/fair.c
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@ -7424,6 +7424,19 @@ static void attach_tasks(struct lb_env *env)
rq_unlock(env->dst_rq, &rf);
}
static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
{
if (cfs_rq->avg.load_avg)
return true;
if (cfs_rq->avg.util_avg)
return true;
return false;
}
#ifdef CONFIG_FAIR_GROUP_SCHED
static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
{
if (cfs_rq->load.weight)
@ -7441,8 +7454,6 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
return true;
}
#ifdef CONFIG_FAIR_GROUP_SCHED
static void update_blocked_averages(int cpu)
{
struct rq *rq = cpu_rq(cpu);
@ -7478,7 +7489,9 @@ static void update_blocked_averages(int cpu)
*/
if (cfs_rq_is_decayed(cfs_rq))
list_del_leaf_cfs_rq(cfs_rq);
else
/* Don't need periodic decay once load/util_avg are null */
if (cfs_rq_has_blocked(cfs_rq))
done = false;
}
@ -7548,7 +7561,7 @@ static inline void update_blocked_averages(int cpu)
update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq);
#ifdef CONFIG_NO_HZ_COMMON
rq->last_blocked_load_update_tick = jiffies;
if (cfs_rq_is_decayed(cfs_rq))
if (!cfs_rq_has_blocked(cfs_rq))
rq->has_blocked_load = 0;
#endif
rq_unlock_irqrestore(rq, &rf);