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| author | Peter Zijlstra <peterz@infradead.org> | 2019-05-29 22:36:44 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2019-08-08 09:09:31 +0200 |
| commit | 67692435c411e5c53a1c588ecca2037aebd81f2e (patch) | |
| tree | 53d9c44e6e80654a60c652493d4b0cc948ce5818 /kernel/sched/stop_task.c | |
| parent | sched: Allow put_prev_task() to drop rq->lock (diff) | |
| download | linux-67692435c411e5c53a1c588ecca2037aebd81f2e.tar.xz linux-67692435c411e5c53a1c588ecca2037aebd81f2e.zip | |
sched: Rework pick_next_task() slow-path
Avoid the RETRY_TASK case in the pick_next_task() slow path.
By doing the put_prev_task() early, we get the rt/deadline pull done,
and by testing rq->nr_running we know if we need newidle_balance().
This then gives a stable state to pick a task from.
Since the fast-path is fair only; it means the other classes will
always have pick_next_task(.prev=NULL, .rf=NULL) and we can simplify.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/aa34d24b36547139248f32a30138791ac6c02bd6.1559129225.git.vpillai@digitalocean.com
Diffstat (limited to 'kernel/sched/stop_task.c')
| -rw-r--r-- | kernel/sched/stop_task.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index 8f414018d5e0..7e1cee4e65b2 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -33,10 +33,11 @@ pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf { struct task_struct *stop = rq->stop; + WARN_ON_ONCE(prev || rf); + if (!stop || !task_on_rq_queued(stop)) return NULL; - put_prev_task(rq, prev); set_next_task_stop(rq, stop); return stop; |