linux-kernel - Re: [PATCH] mm/swap: lru drain on memory reclaim workqueue

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Message-ID: <20160531211308.GE24107@localhost.localdomain>
Date:	Tue, 31 May 2016 17:13:08 -0400
From:	Keith Busch <keith.busch@...el.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/swap: lru drain on memory reclaim workqueue

On Tue, May 31, 2016 at 05:01:16PM -0400, Tejun Heo wrote:
> So, WQ_MEM_RECLAIM on a shared workqueue doesn't make much sense.
> That flag guarantees single concurrency level to the workqueue.  How
> would multiple users of a shared workqueue coordinate around that?
> What prevents one events_mem_unbound user from depending on, say,
> draining lru?  If lru draining requires a rescuer to guarantee forward
> progress under memory pressure, that rescuer worker must be dedicated
> for that purpose and can't be shared.

Gotchya, that fixes my understanding on the rescuer thread operation. In
this case, could we revive your previous proposal for consideration?