From: Mel Gorman <mgorman@techsingularity.net>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Phil Auld <pauld@redhat.com>, Hillf Danton <hdanton@sina.com>,
LKML <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 04/12] sched/fair: reorder enqueue/dequeue_task_fair path
Date: Fri, 14 Feb 2020 08:12:11 +0000 [thread overview]
Message-ID: <20200214081219.26352-5-mgorman@techsingularity.net> (raw)
In-Reply-To: <20200214081219.26352-1-mgorman@techsingularity.net>
From: Vincent Guittot <vincent.guittot@linaro.org>
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
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>
---
kernel/sched/fair.c | 42 ++++++++++++++++++++----------------------
1 file changed, 20 insertions(+), 22 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6c866fb2129c..4395951b1530 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5261,32 +5261,31 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
cfs_rq = cfs_rq_of(se);
enqueue_entity(cfs_rq, se, flags);
- /*
- * end evaluation on encountering a throttled cfs_rq
- *
- * note: in the case of encountering a throttled cfs_rq we will
- * post the final h_nr_running increment below.
- */
- if (cfs_rq_throttled(cfs_rq))
- break;
cfs_rq->h_nr_running++;
cfs_rq->idle_h_nr_running += idle_h_nr_running;
+ /* end evaluation on encountering a throttled cfs_rq */
+ if (cfs_rq_throttled(cfs_rq))
+ goto enqueue_throttle;
+
flags = ENQUEUE_WAKEUP;
}
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
- cfs_rq->h_nr_running++;
- cfs_rq->idle_h_nr_running += idle_h_nr_running;
+ /* end evaluation on encountering a throttled cfs_rq */
if (cfs_rq_throttled(cfs_rq))
- break;
+ goto enqueue_throttle;
update_load_avg(cfs_rq, se, UPDATE_TG);
update_cfs_group(se);
+
+ cfs_rq->h_nr_running++;
+ cfs_rq->idle_h_nr_running += idle_h_nr_running;
}
+enqueue_throttle:
if (!se) {
add_nr_running(rq, 1);
/*
@@ -5347,17 +5346,13 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
cfs_rq = cfs_rq_of(se);
dequeue_entity(cfs_rq, se, flags);
- /*
- * end evaluation on encountering a throttled cfs_rq
- *
- * note: in the case of encountering a throttled cfs_rq we will
- * post the final h_nr_running decrement below.
- */
- if (cfs_rq_throttled(cfs_rq))
- break;
cfs_rq->h_nr_running--;
cfs_rq->idle_h_nr_running -= idle_h_nr_running;
+ /* end evaluation on encountering a throttled cfs_rq */
+ if (cfs_rq_throttled(cfs_rq))
+ goto dequeue_throttle;
+
/* Don't dequeue parent if it has other entities besides us */
if (cfs_rq->load.weight) {
/* Avoid re-evaluating load for this entity: */
@@ -5375,16 +5370,19 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
- cfs_rq->h_nr_running--;
- cfs_rq->idle_h_nr_running -= idle_h_nr_running;
+ /* end evaluation on encountering a throttled cfs_rq */
if (cfs_rq_throttled(cfs_rq))
- break;
+ goto dequeue_throttle;
update_load_avg(cfs_rq, se, UPDATE_TG);
update_cfs_group(se);
+
+ cfs_rq->h_nr_running--;
+ cfs_rq->idle_h_nr_running -= idle_h_nr_running;
}
+dequeue_throttle:
if (!se)
sub_nr_running(rq, 1);
--
2.16.4
next prev parent reply other threads:[~2020-02-14 8:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 8:12 [PATCH 00/12] Reconcile NUMA balancing decisions with the load balancer v2 Mel Gorman
2020-02-14 8:12 ` [PATCH 01/12] sched/fair: Allow a per-CPU kthread waking a task to stack on the same CPU, to fix XFS performance regression Mel Gorman
2020-02-14 8:12 ` [PATCH 02/12] sched/numa: Trace when no candidate CPU was found on the preferred node Mel Gorman
2020-02-14 8:12 ` [PATCH 03/12] sched/numa: Distinguish between the different task_numa_migrate failure cases Mel Gorman
2020-02-14 8:12 ` Mel Gorman [this message]
2020-02-14 8:12 ` [PATCH 05/12] sched/numa: replace runnable_load_avg by load_avg Mel Gorman
2020-02-14 8:12 ` [PATCH 06/12] sched/numa: Use similar logic to the load balancer for moving between domains with spare capacity Mel Gorman
2020-02-14 8:12 ` [PATCH 07/12] sched/fair: replace runnable load average by runnable average Mel Gorman
2020-02-14 8:13 [PATCH 00/12] Reconcile NUMA balancing decisions with the load balancer v2 (resend) Mel Gorman
2020-02-14 8:13 ` [PATCH 04/12] sched/fair: reorder enqueue/dequeue_task_fair path Mel Gorman
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