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Date: Tue, 12 Jul 2016 13:24:46 -0400
From: Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 22/34] mm, page_alloc: wake kswapd based on the highest
 eligible zone
Message-ID: <20160712172446.GB7307@cmpxchg.org>
References: <1467970510-21195-1-git-send-email-mgorman@techsingularity.net>
 <1467970510-21195-23-git-send-email-mgorman@techsingularity.net>
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In-Reply-To: <1467970510-21195-23-git-send-email-mgorman@techsingularity.net>
Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org>, Rik van Riel <riel@surriel.com>, Vlastimil Babka <vbabka@suse.cz>, Minchan Kim <minchan@kernel.org>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, LKML <linux-kernel@vger.kernel.org>

On Fri, Jul 08, 2016 at 10:34:58AM +0100, Mel Gorman wrote:
> The ac_classzone_idx is used as the basis for waking kswapd and that is based
> on the preferred zoneref. If the preferred zoneref's first zone is lower
> than what is available on other nodes, it's possible that kswapd is woken
> on a zone with only higher, but still eligible, zones. As classzone_idx
> is strictly adhered to now, it causes a problem because eligible pages
> are skipped.
> 
> For example, node 0 has only DMA32 and node 1 has only NORMAL. An allocating
> context running on node 0 may wake kswapd on node 1 telling it to skip
> all NORMAL pages.
> 
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

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