Commit a489a03e authored Jul 22, 2014 by Lai Jiangshan Committed by Tejun Heo Jul 22, 2014

workqueue: remove an unneeded UNBOUND test before waking up the next worker



In process_one_work():

	if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool))
		wake_up_worker(pool);

the first test is unneeded.  Even if the first test is removed, it
doesn't affect the wake-up logic for WORKER_UNBOUND, and it will not
introduce any useless wake-ups for normal per-cpu workers since
nr_running is always >= 1.  It will introduce useless/redundant
wake-ups for CPU_INTENSIVE, but this case is rare and the next patch
will also remove this redundant wake-up.

tj: Minor updates to the description and comment.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent d8ca83e6

kernel/workqueue.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -2048,10 +2048,13 @@ __acquires(&pool->lock)
		worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);

		/*
		* Unbound pool isn't concurrency managed and work items should be
		* executed ASAP. Wake up another worker if necessary.
		* Wake up another worker if necessary. The condition is always
		* false for normal per-cpu workers since nr_running would always
		* be >= 1 at this point. This is used to chain execution of the
		* pending work items for WORKER_NOT_RUNNING workers such as the
		* UNBOUND ones.
		*/
		if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool))
		if (need_more_worker(pool))
		wake_up_worker(pool);

		/*

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