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sched/fair: Fix unthrottle_cfs_rq() for leaf_cfs_rq list 

Although not exactly identical, unthrottle_cfs_rq() and enqueue_task_fair()
are quite close and follow the same sequence for enqueuing an entity in the
cfs hierarchy. Modify unthrottle_cfs_rq() to use the same pattern as
enqueue_task_fair(). This fixes a problem already faced with the latter and
add an optimization in the last for_each_sched_entity loop.

Fixes: fe61468b2c (sched/fair: Fix enqueue_task_fair warning)
Reported-by Tao Zhou <zohooouoto@zoho.com.cn>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Link: https://lkml.kernel.org/r/20200513135528.4742-1-vincent.guittot@linaro.org
This commit is contained in:
Vincent Guittot 2020-05-13 15:55:28 +02:00 committed by Peter Zijlstra
parent ad32bb41fc
commit 39f23ce07b
1 changed files with 31 additions and 13 deletions
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44
kernel/sched/fair.c
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@ -4774,7 +4774,6 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
struct rq *rq = rq_of(cfs_rq);
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
struct sched_entity *se;
int enqueue = 1;
long task_delta, idle_task_delta;
se = cfs_rq->tg->se[cpu_of(rq)];
@ -4798,26 +4797,44 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
idle_task_delta = cfs_rq->idle_h_nr_running;
for_each_sched_entity(se) {
if (se->on_rq)
enqueue = 0;
break;
cfs_rq = cfs_rq_of(se);
if (enqueue) {
enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
} else {
update_load_avg(cfs_rq, se, 0);
se_update_runnable(se);
}
enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
cfs_rq->h_nr_running += task_delta;
cfs_rq->idle_h_nr_running += idle_task_delta;
/* end evaluation on encountering a throttled cfs_rq */
if (cfs_rq_throttled(cfs_rq))
break;
goto unthrottle_throttle;
}
if (!se)
add_nr_running(rq, task_delta);
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
update_load_avg(cfs_rq, se, UPDATE_TG);
se_update_runnable(se);
cfs_rq->h_nr_running += task_delta;
cfs_rq->idle_h_nr_running += idle_task_delta;
/* end evaluation on encountering a throttled cfs_rq */
if (cfs_rq_throttled(cfs_rq))
goto unthrottle_throttle;
/*
* One parent has been throttled and cfs_rq removed from the
* list. Add it back to not break the leaf list.
*/
if (throttled_hierarchy(cfs_rq))
list_add_leaf_cfs_rq(cfs_rq);
}
/* At this point se is NULL and we are at root level*/
add_nr_running(rq, task_delta);
unthrottle_throttle:
/*
* The cfs_rq_throttled() breaks in the above iteration can result in
* incomplete leaf list maintenance, resulting in triggering the
@ -4826,7 +4843,8 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
list_add_leaf_cfs_rq(cfs_rq);
if (list_add_leaf_cfs_rq(cfs_rq))
break;
}
assert_list_leaf_cfs_rq(rq);