linux-kernel - [PATCH 6/7] workqueue: Remove the cacheline_aligned for nr

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Message-Id: <20211207073543.61092-7-jiangshanlai@gmail.com>
Date:   Tue,  7 Dec 2021 15:35:42 +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 6/7] workqueue: Remove the cacheline_aligned for nr_running

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

nr_running is never modified remotely after the schedule callback in
wakeup path is removed.

Rather nr_running is often accessed with other fields in the pool
together, so the cacheline_aligned for nr_running isn't needed.

Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 kernel/workqueue.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 256f552e9513..33f1106b4f99 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -154,6 +154,9 @@ struct worker_pool {
 
 	unsigned long		watchdog_ts;	/* L: watchdog timestamp */
 
+	/* The current concurrency level. */
+	atomic_t		nr_running;
+
 	struct list_head	worklist;	/* L: list of pending works */
 
 	int			nr_workers;	/* L: total number of workers */
@@ -177,19 +180,12 @@ struct worker_pool {
 	struct hlist_node	hash_node;	/* PL: unbound_pool_hash node */
 	int			refcnt;		/* PL: refcnt for unbound pools */
 
-	/*
-	 * The current concurrency level.  As it's likely to be accessed
-	 * from other CPUs during try_to_wake_up(), put it in a separate
-	 * cacheline.
-	 */
-	atomic_t		nr_running ____cacheline_aligned_in_smp;
-
 	/*
 	 * Destruction of pool is RCU protected to allow dereferences
 	 * from get_work_pool().
 	 */
 	struct rcu_head		rcu;
-} ____cacheline_aligned_in_smp;
+};
 
 /*
  * The per-pool workqueue.  While queued, the lower WORK_STRUCT_FLAG_BITS
-- 
2.19.1.6.gb485710b