linux-kernel - Re: [PATCH] fbdev: Remove deprecated create_singlethread

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Message-ID: <20160702113635.GF17431@htj.duckdns.org>
Date:	Sat, 2 Jul 2016 06:36:35 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Bhaktipriya Shridhar <bhaktipriya96@...il.com>
Cc:	Tomi Valkeinen <tomi.valkeinen@...com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	linux-fbdev@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fbdev: Remove deprecated create_singlethread_workqueue

On Sat, Jul 02, 2016 at 02:09:23PM +0530, Bhaktipriya Shridhar wrote:
> The workqueue "esd_wq" has only a single workitem(&md->esd_work)
> and hence doesn't require ordering. Also, it is not being used on a
> memory reclaim path. Hence, the singlethreaded workqueue has been
> replaced with the use of system_wq.
> 
> System workqueues have been able to handle high level of concurrency
> for a long time now and hence it's not required to have a singlethreaded
> workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue
> created with create_singlethread_workqueue(), system_wq allows multiple
> work items to overlap executions even on the same CPU; however, a
> per-cpu workqueue doesn't have any CPU locality or global ordering
> guarantee unless the target CPU is explicitly specified and thus the
> increase of local concurrency shouldn't make any difference.
> 
> mipid_esd_stop_check () calls cancel_delayed_work() in mipid_cleanup()
> to ensure that there are no pending tasks while disconnecting the driver.
> 
> Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@...il.com>

Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun