From a489a03eca74cd1d5ac771f4b2ae2c826aab0b30 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 22 Jul 2014 13:01:59 +0800 Subject: [PATCH] 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 Signed-off-by: Tejun Heo --- kernel/workqueue.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index d3444169e261..c20cfbe89194 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -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); /*