linux-kernel - [RFC] workqueue: avoiding unbounded wq on isolated CPUs by default

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Message-Id: <9e53de7c91c885ee255e16ee25f401d9eedf08d9.1437067317.git.bristot@redhat.com>
Date:	Thu, 16 Jul 2015 16:16:23 -0300
From:	Daniel Bristot de Oliveira <bristot@...hat.com>
To:	Tejun Heo <tj@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Cc:	Lai Jiangshan <jiangshanlai@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Rik van Riel <riel@...hat.com>,
	"Luis Claudio R. Goncalves" <lclaudio@...g.org>
Subject: [RFC] workqueue: avoiding unbounded wq on isolated CPUs by default

By default, unbounded workqueues run on all CPUs, which includes
isolated CPUs. This patch avoids unbounded workqueues running on
isolated CPUs by default, keeping the current behavior when no
CPUs were isolated.

Signed-off-by: Daniel Bristot de Oliveira <bristot@...hat.com>
---
 kernel/workqueue.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 4c4f061..14d17f4 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5217,7 +5217,10 @@ static int __init init_workqueues(void)
 	WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
 
 	BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
-	cpumask_copy(wq_unbound_cpumask, cpu_possible_mask);
+
+	/* by default, run unbound wq on non-isolated CPUs */
+	cpumask_andnot(wq_unbound_cpumask, cpu_possible_mask,
+		       cpu_isolated_map);
 
 	pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
 
-- 
2.1.0

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