sched/fair: Reorder enqueue/dequeue_task_fair path
[ Upstream commit 6d4d22468d
]
The walk through the cgroup hierarchy during the enqueue/dequeue of a task
is split in 2 distinct parts for throttled cfs_rq without any added value
but making code less readable.
Change the code ordering such that everything related to a cfs_rq
(throttled or not) will be done in the same loop.
In addition, the same steps ordering is used when updating a cfs_rq:
- update_load_avg
- update_cfs_group
- update *h_nr_running
This reordering enables the use of h_nr_running in PELT algorithm.
No functional and performance changes are expected and have been noticed
during tests.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: "Dietmar Eggemann <dietmar.eggemann@arm.com>"
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Link: https://lore.kernel.org/r/20200224095223.13361-5-mgorman@techsingularity.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
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@ -5232,32 +5232,31 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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cfs_rq = cfs_rq_of(se);
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enqueue_entity(cfs_rq, se, flags);
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/*
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* end evaluation on encountering a throttled cfs_rq
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*
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* note: in the case of encountering a throttled cfs_rq we will
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* post the final h_nr_running increment below.
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*/
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if (cfs_rq_throttled(cfs_rq))
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break;
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cfs_rq->h_nr_running++;
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cfs_rq->idle_h_nr_running += idle_h_nr_running;
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/* end evaluation on encountering a throttled cfs_rq */
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if (cfs_rq_throttled(cfs_rq))
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goto enqueue_throttle;
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flags = ENQUEUE_WAKEUP;
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}
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for_each_sched_entity(se) {
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cfs_rq = cfs_rq_of(se);
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cfs_rq->h_nr_running++;
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cfs_rq->idle_h_nr_running += idle_h_nr_running;
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/* end evaluation on encountering a throttled cfs_rq */
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if (cfs_rq_throttled(cfs_rq))
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break;
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goto enqueue_throttle;
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update_load_avg(cfs_rq, se, UPDATE_TG);
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update_cfs_group(se);
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cfs_rq->h_nr_running++;
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cfs_rq->idle_h_nr_running += idle_h_nr_running;
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}
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enqueue_throttle:
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if (!se) {
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add_nr_running(rq, 1);
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/*
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@ -5317,17 +5316,13 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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cfs_rq = cfs_rq_of(se);
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dequeue_entity(cfs_rq, se, flags);
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/*
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* end evaluation on encountering a throttled cfs_rq
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*
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* note: in the case of encountering a throttled cfs_rq we will
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* post the final h_nr_running decrement below.
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*/
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if (cfs_rq_throttled(cfs_rq))
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break;
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cfs_rq->h_nr_running--;
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cfs_rq->idle_h_nr_running -= idle_h_nr_running;
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/* end evaluation on encountering a throttled cfs_rq */
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if (cfs_rq_throttled(cfs_rq))
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goto dequeue_throttle;
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/* Don't dequeue parent if it has other entities besides us */
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if (cfs_rq->load.weight) {
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/* Avoid re-evaluating load for this entity: */
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@ -5345,16 +5340,19 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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for_each_sched_entity(se) {
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cfs_rq = cfs_rq_of(se);
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cfs_rq->h_nr_running--;
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cfs_rq->idle_h_nr_running -= idle_h_nr_running;
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/* end evaluation on encountering a throttled cfs_rq */
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if (cfs_rq_throttled(cfs_rq))
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break;
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goto dequeue_throttle;
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update_load_avg(cfs_rq, se, UPDATE_TG);
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update_cfs_group(se);
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cfs_rq->h_nr_running--;
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cfs_rq->idle_h_nr_running -= idle_h_nr_running;
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}
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dequeue_throttle:
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if (!se)
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sub_nr_running(rq, 1);
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