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Date: Fri, 10 Jan 2014 17:51:18 -0500
From: Rik van Riel <riel@redhat.com>
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To: Johannes Weiner <hannes@cmpxchg.org>,
        Andrew Morton <akpm@linux-foundation.org>
CC: Andi Kleen <andi@firstfloor.org>, Andrea Arcangeli <aarcange@redhat.com>,
        Bob Liu <bob.liu@oracle.com>, Christoph Hellwig <hch@infradead.org>,
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        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Luigi Semenzato <semenzato@google.com>, Mel Gorman <mgorman@suse.de>,
        Metin Doslu <metin@citusdata.com>,
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        Minchan Kim <minchan.kim@gmail.com>,
        Ozgun Erdogan <ozgun@citusdata.com>,
        Peter Zijlstra <peterz@infradead.org>,
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        linux-kernel@vger.kernel.org
Subject: Re: [patch 7/9] mm: thrash detection-based file cache sizing
References: <1389377443-11755-1-git-send-email-hannes@cmpxchg.org> <1389377443-11755-8-git-send-email-hannes@cmpxchg.org>
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On 01/10/2014 01:10 PM, Johannes Weiner wrote:

> This patch solves one half of the problem by decoupling the ability to
> detect working set changes from the inactive list size.  By
> maintaining a history of recently evicted file pages it can detect
> frequently used pages with an arbitrarily small inactive list size,
> and subsequently apply pressure on the active list based on actual
> demand for cache, not just overall eviction speed.
> 
> Every zone maintains a counter that tracks inactive list aging speed.
> When a page is evicted, a snapshot of this counter is stored in the
> now-empty page cache radix tree slot.  On refault, the minimum access
> distance of the page can be assessed, to evaluate whether the page
> should be part of the active list or not.
> 
> This fixes the VM's blindness towards working set changes in excess of
> the inactive list.  And it's the foundation to further improve the
> protection ability and reduce the minimum inactive list size of 50%.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Reviewed-by: Rik van Riel <riel@redhat.com>

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