sched/fair: Reorder throttle_cfs_rq() path

As commit:

  39f23ce07b93 ("sched/fair: Fix unthrottle_cfs_rq() for leaf_cfs_rq list")

does in unthrottle_cfs_rq(), throttle_cfs_rq() can also use the same
pattern as dequeue_task_fair().

No functional changes.

Signed-off-by: Peng Wang <rocking@linux.alibaba.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Phil Auld <pauld@redhat.com>
Cc: Ben Segall <bsegall@google.com>
Link: https://lore.kernel.org/r/f11dd2e3ab35cc538e2eb57bf0c99b6eaffce127.1604973978.git.rocking@linux.alibaba.com

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 52cacfc..2755a7e 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4788,25 +4788,37 @@ static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
                struct cfs_rq *qcfs_rq = cfs_rq_of(se);
                /* throttled entity or throttle-on-deactivate */
                if (!se->on_rq)
-                       break;
+                       goto done;
 
-               if (dequeue) {
-                       dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
-               } else {
-                       update_load_avg(qcfs_rq, se, 0);
-                       se_update_runnable(se);
-               }
+               dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
 
                qcfs_rq->h_nr_running -= task_delta;
                qcfs_rq->idle_h_nr_running -= idle_task_delta;
 
-               if (qcfs_rq->load.weight)
-                       dequeue = 0;
+               if (qcfs_rq->load.weight) {
+                       /* Avoid re-evaluating load for this entity: */
+                       se = parent_entity(se);
+                       break;
+               }
        }
 
-       if (!se)
-               sub_nr_running(rq, task_delta);
+       for_each_sched_entity(se) {
+               struct cfs_rq *qcfs_rq = cfs_rq_of(se);
+               /* throttled entity or throttle-on-deactivate */
+               if (!se->on_rq)
+                       goto done;
+
+               update_load_avg(qcfs_rq, se, 0);
+               se_update_runnable(se);
 
+               qcfs_rq->h_nr_running -= task_delta;
+               qcfs_rq->idle_h_nr_running -= idle_task_delta;
+       }
+
+       /* At this point se is NULL and we are at root level*/
+       sub_nr_running(rq, task_delta);
+
+done:
        /*
         * Note: distribution will already see us throttled via the
         * throttled-list.  rq->lock protects completion.