linux-kernel - [PATCH 2/7] workqueue: Remove the advanced kicking of the idle workers in rebind

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Message-Id: <20211207073543.61092-3-jiangshanlai@gmail.com>
Date:   Tue,  7 Dec 2021 15:35:38 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>
Cc:     Lai Jiangshan <laijs@...ux.alibaba.com>,
        Lai Jiangshan <jiangshanlai@...il.com>
Subject: [PATCH 2/7] workqueue: Remove the advanced kicking of the idle workers in rebind_workers()

From: Lai Jiangshan <laijs@...ux.alibaba.com>

The commit 6d25be5782e4 ("sched/core, workqueues: Distangle worker
accounting from rq lock") changed the schedule callbacks for workqueue
and removed the local-wake-up functionality.

Now the wakingup of workers is done by normal fashion and workers not
yet migrated to the specific CPU in concurrency managed pool can also
be woken up by workers that already bound to the specific cpu now.

So this advanced kicking of the idle workers to migrate them to the
associated CPU is unneeded now.

Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 kernel/workqueue.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 312b806b3956..ba8cf5f5e7fa 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5077,17 +5077,6 @@ static void rebind_workers(struct worker_pool *pool)
 	for_each_pool_worker(worker, pool) {
 		unsigned int worker_flags = worker->flags;
 
-		/*
-		 * A bound idle worker should actually be on the runqueue
-		 * of the associated CPU for local wake-ups targeting it to
-		 * work.  Kick all idle workers so that they migrate to the
-		 * associated CPU.  Doing this in the same loop as
-		 * replacing UNBOUND with REBOUND is safe as no worker will
-		 * be bound before @pool->lock is released.
-		 */
-		if (worker_flags & WORKER_IDLE)
-			wake_up_process(worker->task);
-
 		/*
 		 * We want to clear UNBOUND but can't directly call
 		 * worker_clr_flags() or adjust nr_running.  Atomically
-- 
2.19.1.6.gb485710b