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.

Lai Jiangshan committed 12 years ago

Commit a489a031 parent d8ca83e1 file · +6 −3Browse files

Showing the changes to kernel/workqueue.c (1 of 1 file). Show all

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kernel/workqueue.c+6−3

@@ -2048,10 +2048,13 @@ __acquires(&pool->lock) · 2047 unmodified lines
2048	2048	worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
2049	2049
2050	2050	/*
2051		− * Unbound pool isn't concurrency managed and work items should be
2052		− * executed ASAP. Wake up another worker if necessary.
	2051	+ * Wake up another worker if necessary. The condition is always
	2052	+ * false for normal per-cpu workers since nr_running would always
	2053	+ * be >= 1 at this point. This is used to chain execution of the
	2054	+ * pending work items for WORKER_NOT_RUNNING workers such as the
	2055	+ * UNBOUND ones.
2053	2056	*/
2054		− if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool))
	2057	+ if (need_more_worker(pool))
2055	2058	wake_up_worker(pool);
2056	2059
2057	2060	/*