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Message-ID: <1406005330-11864-1-git-send-email-laijs@cn.fujitsu.com> Date: Tue, 22 Jul 2014 13:01:59 +0800 From: Lai Jiangshan <laijs@...fujitsu.com> To: <linux-kernel@...r.kernel.org> CC: Tejun Heo <tj@...nel.org>, Lai Jiangshan <laijs@...fujitsu.com> Subject: [PATCH 1/2 V2] workqueue: remove unneeded test before wake up next worker In this code: if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) wake_up_worker(pool); the first test is unneeded. Even the first test is removed, it doesn't affect the wake-up logic when WORKER_UNBOUND. And it will not introduce any useless wake-up when !WORKER_UNBOUND since the nr_running >= 1 except only one case. It will introduce useless/redundant wake-up when cpu_intensive, but this case is rare and next patch will also remove this redundant wake-up. Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com> --- kernel/workqueue.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index a791a8c..cd75689 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. It is a no-op + * when the current worker is concurrency managed since + * pool->nr_running >= 1. But it is required for non-concurrency + * managed workers, mainly for unbound pool which requries + * chain execution of currently pending work items ASAP. */ - if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) + if (need_more_worker(pool)) wake_up_worker(pool); /* -- 1.7.4.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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