Re: [PATCH 06/21] workqueue: separate out pools locking intopools_mutex

From: Tejun Heo
Date: Wed Mar 20 2013 - 13:58:30 EST


On Wed, Mar 20, 2013 at 03:28:06AM +0800, Lai Jiangshan wrote:
> currently wq_mutext protects:
>
> * worker_pool_idr and unbound_pool_hash
> * pool->refcnt
> * workqueues list
> * workqueue->flags, ->nr_drainers
> * workqueue_freezing
>
> We can see that it protects very different things.
> So we need to split it and introduce a pools_mutex to protect:
>
> * worker_pool_idr and unbound_pool_hash
> * pool->refcnt
>
> (all are pools related field.)
>
> workqueue_freezing is special, it is protected by both of wq_mutext
> pools_mutex. All are because get_unbound_pool() need to read it,
> which are because POOL_FREEZING is a bad design which will be fixed later.
>
> Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>

Umm... I'm not sure about this one. What's the benefit of further
splitting wq_mutex? There's no identified bottleneck. It just makes
things more complex.

Thanks.

--
tejun
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