From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 15/15] readahead: pagecache context based mmap read-around
Date: Thu, 25 Feb 2010 20:33:32 -0500
Message-ID: <4B8724EC.1090904@redhat.com>
References: <20100224031001.026464755@intel.com> <20100224031055.738182009@intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Jens Axboe <jens.axboe@oracle.com>, Nick Piggin <npiggin@suse.de>,
        Chris Mason <chris.mason@oracle.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Clemens Ladisch <clemens@ladisch.de>,
        Olivier Galibert <galibert@pobox.com>, Vivek Goyal <vgoyal@redhat.com>,
        Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>,
        Matt Mackall <mpm@selenic.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        linux-fsdevel@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <20100224031055.738182009@intel.com>
Sender: owner-linux-mm@kvack.org
List-Id: linux-fsdevel.vger.kernel.org

On 02/23/2010 10:10 PM, Wu Fengguang wrote:
> Do mmap read-around when there are cached pages in the nearby 256KB
> (covered by one radix tree node).
>
> There is a failure case though: for a sequence of page faults at page
> index 64*i+1, i=1,2,3,..., this heuristic will keep doing pointless
> read-arounds.  Hopefully the pattern won't appear in real workloads.
> Note that the readahead heuristic has similiar failure case.
>
> CC: Nick Piggin<npiggin@suse.de>
> Signed-off-by: Wu Fengguang<fengguang.wu@intel.com>

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

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>