From: Vincent Guittot <vincent.guittot@linaro.org>
To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de,
linux-kernel@vger.kernel.org
Cc: pauld@redhat.com, ouwen210@hotmail.com, pkondeti@codeaurora.org,
Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH v3] sched/fair: fix unthrottle_cfs_rq for leaf_cfs_rq list
Date: Wed, 13 May 2020 15:55:28 +0200 [thread overview]
Message-ID: <20200513135528.4742-1-vincent.guittot@linaro.org> (raw)
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.
Reported-by Tao Zhou <zohooouoto@zoho.com.cn>
Reviewed-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
v3 changes:
- remove the unused enqueue variable
kernel/sched/fair.c | 42 ++++++++++++++++++++++++++++++------------
1 file changed, 30 insertions(+), 12 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4e12ba882663..9a58874ef104 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4792,7 +4792,6 @@ 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)];
@@ -4816,26 +4815,44 @@ 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);
+ 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))
+ goto unthrottle_throttle;
+ }
+
+ for_each_sched_entity(se) {
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);
- }
+
+ 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))
- break;
+ 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);
}
- if (!se)
- add_nr_running(rq, task_delta);
+ /* 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
@@ -4844,7 +4861,8 @@ 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);
--
2.17.1
next reply other threads:[~2020-05-13 13:55 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-13 13:55 Vincent Guittot [this message]
2020-05-13 18:25 ` [PATCH v3] sched/fair: fix unthrottle_cfs_rq for leaf_cfs_rq list bsegall
2020-05-19 18:44 ` [tip: sched/urgent] sched/fair: Fix unthrottle_cfs_rq() " tip-bot2 for Vincent Guittot
2020-11-18 22:56 [PATCH v3] sched/fair: fix unthrottle_cfs_rq " Guilherme G. Piccoli
2020-11-18 23:30 ` Tao Zhou
2020-11-18 23:50 ` Tao Zhou
2020-11-19 0:33 ` Tao Zhou
2020-11-19 8:36 ` Vincent Guittot
2020-11-19 11:34 ` Guilherme G. Piccoli
2020-11-19 13:25 ` Vincent Guittot
2020-11-19 14:07 ` Guilherme Piccoli
2021-06-24 10:29 ` Po-Hsu Lin
2021-06-24 12:31 ` Vincent Guittot
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