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| author | Steven Rostedt <rostedt@goodmis.org> | 2013-03-18 15:12:49 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2013-10-24 11:06:32 -0400 |
| commit | 386d4256ba670dacfcf523862601e64b7e63b254 (patch) | |
| tree | 2c7f3b5601ea90c6f9738bc11c169a19bd08e223 | |
| parent | 344b93efce99afe65425a5645beb1e38b16c04b2 (diff) | |
| download | linux-rt-386d4256ba670dacfcf523862601e64b7e63b254.tar.gz | |
sched/workqueue: Only wake up idle workers if not blocked on sleeping spin lock
In -rt, most spin_locks() turn into mutexes. One of these spin_lock
conversions is performed on the workqueue gcwq->lock. When the idle
worker is worken, the first thing it will do is grab that same lock and
it too will block, possibly jumping into the same code, but because
nr_running would already be decremented it prevents an infinite loop.
But this is still a waste of CPU cycles, and it doesn't follow the method
of mainline, as new workers should only be woken when a worker thread is
truly going to sleep, and not just blocked on a spin_lock().
Check the saved_state too before waking up new workers.
Cc: stable-rt@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
| -rw-r--r-- | kernel/sched.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 96dd9c2f9581..59bb8bcf34de 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4436,8 +4436,10 @@ static inline void sched_submit_work(struct task_struct *tsk) /* * If a worker went to sleep, notify and ask workqueue whether * it wants to wake up a task to maintain concurrency. + * Only call wake up if prev isn't blocked on a sleeping + * spin lock. */ - if (tsk->flags & PF_WQ_WORKER) + if (tsk->flags & PF_WQ_WORKER && !tsk->saved_state) wq_worker_sleeping(tsk); /* |