From: Johannes Weiner <hannes@cmpxchg.org>
To: Mel Gorman <mgorman@suse.de>
Cc: 'Andrew Morton' <akpm@linux-foundation.org>,
Hillf Danton <hillf.zj@alibaba-inc.com>,
'Michal Hocko' <mhocko@suse.com>,
'Minchan Kim' <minchan.kim@gmail.com>,
'Rik van Riel' <riel@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm, vmscan: Clear PGDAT_WRITEBACK when zone is balanced
Date: Fri, 3 Feb 2017 16:24:11 -0500 [thread overview]
Message-ID: <20170203212411.GA12133@cmpxchg.org> (raw)
In-Reply-To: <20170203203222.gq7hk66yc36lpgtb@suse.de>
On Fri, Feb 03, 2017 at 08:32:22PM +0000, Mel Gorman wrote:
> Hillf Danton pointed out that since commit 1d82de618dd ("mm, vmscan:
> make kswapd reclaim in terms of nodes") that PGDAT_WRITEBACK is no longer
> cleared. It was not noticed as triggering it requires pages under writeback
> to cycle twice through the LRU and before kswapd gets stalled. Historically,
> such issues tended to occur on small machines writing heavily to slow
> storage such as a USB stick. Once kswapd stalls, direct reclaim stalls may
> be higher but due to the fact that memory pressure is requires, it would not
> be very noticable. Michal Hocko suggested removing the flag entirely but
> the conservative fix is to restore the intended PGDAT_WRITEBACK behaviour
> and clear the flag when a suitable zone is balanced.
>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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next prev parent reply other threads:[~2017-02-03 21:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-03 20:32 Mel Gorman
2017-02-03 21:24 ` Johannes Weiner [this message]
2017-02-04 3:09 ` Hillf Danton
2017-02-05 10:11 ` Michal Hocko
2017-02-05 10:13 ` Michal Hocko
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