From: Tejun Heo <tj@kernel.org>
To: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
linux-kernel@vger.kernel.org, Christoph Lameter <cl@linux.com>,
Kevin Hilman <khilman@linaro.org>,
Mike Galbraith <bitbucket@online.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Viresh Kumar <viresh.kumar@linaro.org>
Subject: Re: [PATCH 4/4 V5] workqueue: Allow modifying low level unbound workqueue cpumask
Date: Wed, 1 Apr 2015 11:52:12 -0400 [thread overview]
Message-ID: <20150401155212.GO9974@htj.duckdns.org> (raw)
In-Reply-To: <551BAD5A.2070205@cn.fujitsu.com>
On Wed, Apr 01, 2015 at 04:33:30PM +0800, Lai Jiangshan wrote:
> The missing case:
> (@L & @U) is not empty but (@L & @U @O) is empty.
>
> In my old code (V5 patchset), the dfl_pwq uses (@L & @U), the scheduler will
> use cpu_possible_mask instead due to there is no cpu onlined among all cpu in (@L & @U).
> It is bad, the pwq is NOT controlled by @L nor @U now.
>
> I think we may use @U for the dfl_pwq in this case. But it will introduces
> a problem:
>
> When (@L & @U) has online cpu, the dfl_pwq's cpumaks is (@L & @U).
> when (@L & @U) has no online cpu, the dfl_pwq's cpumask is @U.
> It means dfl_pwq may need to be reallocated during the cpuhotplug-add/remove
> and it means wq_update_unbound_numa() can fail.
>
> Frederic, TJ, any comments about this case?
> TJ, would you like to make wq_update_unbound_numa() be failure-able?
The goal is making @L behave as cpu_possible_mask for workqueues,
right? If @L & @U is empty, fallback to @L. If @L & @O is empty,
leave it to the scheduler.
Thanks.
--
tejun
next prev parent reply other threads:[~2015-04-01 15:52 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-12 5:00 [PATCH 0/4] workqueue: Introduce low-level unbound wq sysfs cpumask v4 Lai Jiangshan
2015-03-12 5:00 ` [PATCH 1/4] workqueue: Reorder sysfs code Lai Jiangshan
2015-03-12 5:00 ` [PATCH 2/4] workqueue: split apply_workqueue_attrs() into 3 stages Lai Jiangshan
2015-03-12 5:00 ` [PATCH 3/4] workqueue: Create low-level unbound workqueues cpumask Lai Jiangshan
2015-03-12 17:33 ` Christoph Lameter
2015-03-13 23:49 ` Kevin Hilman
2015-03-14 0:52 ` Kevin Hilman
2015-03-14 7:52 ` Lai Jiangshan
2015-03-16 17:12 ` Kevin Hilman
2015-03-16 17:25 ` Frederic Weisbecker
2015-03-16 19:38 ` Kevin Hilman
2015-03-12 5:00 ` [PATCH 4/4] workqueue: Allow modifying low level unbound workqueue cpumask Lai Jiangshan
2015-03-12 17:42 ` Christoph Lameter
2015-03-13 1:38 ` Lai Jiangshan
2015-03-13 7:49 ` Lai Jiangshan
2015-03-12 17:49 ` [PATCH 0/4] workqueue: Introduce low-level unbound wq sysfs cpumask v4 Frederic Weisbecker
2015-03-13 6:02 ` Mike Galbraith
2015-03-18 4:40 ` [PATCH 0/4 V5] workqueue: Introduce low-level unbound wq sysfs cpumask v5 Lai Jiangshan
2015-03-18 4:40 ` [PATCH 1/4 V5] workqueue: Reorder sysfs code Lai Jiangshan
2015-03-24 15:41 ` Tejun Heo
2015-03-18 4:40 ` [PATCH 2/4 V5] workqueue: split apply_workqueue_attrs() into 3 stages Lai Jiangshan
2015-03-24 15:55 ` Tejun Heo
2015-03-18 4:40 ` [PATCH 3/4 V5] workqueue: Create low-level unbound workqueues cpumask Lai Jiangshan
2015-03-18 4:40 ` [PATCH 4/4 V5] workqueue: Allow modifying low level unbound workqueue cpumask Lai Jiangshan
2015-03-24 17:31 ` Tejun Heo
2015-03-31 7:46 ` Lai Jiangshan
2015-04-01 8:33 ` Lai Jiangshan
2015-04-01 15:52 ` Tejun Heo [this message]
2015-03-19 8:54 ` [PATCH 0/4 V5] workqueue: Introduce low-level unbound wq sysfs cpumask v5 Mike Galbraith
2015-04-02 11:14 ` [PATCH 0/4 V6] " Lai Jiangshan
2015-04-02 11:14 ` [PATCH 1/4 V6] workqueue: Reorder sysfs code Lai Jiangshan
2015-04-06 15:22 ` Tejun Heo
2015-04-02 11:14 ` [PATCH 2/4 V6] workqueue: split apply_workqueue_attrs() into 3 stages Lai Jiangshan
2015-04-06 15:39 ` Tejun Heo
2015-04-02 11:14 ` [PATCH 3/4 V6] workqueue: Create low-level unbound workqueues cpumask Lai Jiangshan
2015-04-02 11:14 ` [PATCH 4/4 V6] workqueue: Allow modifying low level unbound workqueue cpumask Lai Jiangshan
2015-04-06 15:53 ` Tejun Heo
2015-04-07 1:25 ` Lai Jiangshan
2015-04-07 1:58 ` Tejun Heo
2015-04-07 2:33 ` Lai Jiangshan
2015-04-07 11:26 ` [PATCH 1/3 V7] workqueue: split apply_workqueue_attrs() into 3 stages Lai Jiangshan
2015-04-07 11:26 ` [PATCH 2/3 V7] workqueue: Create low-level unbound workqueues cpumask Lai Jiangshan
2015-04-07 11:26 ` [PATCH 3/3 V7] workqueue: Allow modifying low level unbound workqueue cpumask Lai Jiangshan
2015-04-22 19:39 ` Tejun Heo
2015-04-22 23:02 ` Frederic Weisbecker
2015-04-23 6:29 ` Mike Galbraith
2015-04-17 14:57 ` [PATCH 1/3 V7] workqueue: split apply_workqueue_attrs() into 3 stages Tejun Heo
2015-04-20 3:21 ` Lai Jiangshan
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