Date: Thu, 13 Nov 2008 19:27:29 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Rik van Riel <riel@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH -mm] vmscan: bail out of page reclaim after
 swap_cluster_max pages
Message-Id: <20081113192729.7d8eb133.akpm@linux-foundation.org>
In-Reply-To: <20081113171208.6985638e@bree.surriel.com>
References: <20081113171208.6985638e@bree.surriel.com>
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On Thu, 13 Nov 2008 17:12:08 -0500 Rik van Riel <riel@redhat.com> wrote:

> Sometimes the VM spends the first few priority rounds rotating back
> referenced pages and submitting IO.  Once we get to a lower priority,
> sometimes the VM ends up freeing way too many pages.
> 
> The fix is relatively simple: in shrink_zone() we can check how many
> pages we have already freed and break out of the loop.
> 
> However, in order to do this we do need to know how many pages we already
> freed, so move nr_reclaimed into scan_control.

There was a reason for not doing this, but I forget what it was.  It might require
some changelog archeology.  iirc it was to do with balancing scanning rates
between the various things which we scan.
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