linux-kernel - Re: [PATCH v3] ASoC: Remove deprecated create_singlethread

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Message-ID: <20160831142648.GP12660@htj.duckdns.org>
Date:   Wed, 31 Aug 2016 10:26:48 -0400
From:   Tejun Heo <tj@...nel.org>
To:     Bhaktipriya Shridhar <bhaktipriya96@...il.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] ASoC: Remove deprecated create_singlethread_workqueue

On Wed, Aug 31, 2016 at 12:57:09AM +0530, Bhaktipriya Shridhar wrote:
> The workqueue "dac33_wq" queues a single work item &dac33->work and hence
> doesn't require ordering. Also, it is not being used on a memory reclaim
> path. Hence, it has been converted to use system_wq.
> 
> The work item has been flushed in dac33_soc_remove to ensure that
> there are no pending tasks while disconnecting the driver.
> 
> The workqueue "post_msg_wq" queues a single work item
> &drv->ipc_post_msg_wq and hence doesn't require ordering. Also, it is
> not being used on a memory reclaim path. Hence, it has been converted to
> use system_wq.
> 
> The work item has been flushed in sst_context_cleanup to ensure that
> there are no pending tasks while disconnecting the driver.
> 
> 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.
> 
> Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@...il.com>

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

Thanks.

-- 
tejun