linux-kernel - Re: [PATCH 14/15] readahead: reduce MMAP

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Message-ID: <4B870AF1.90300@redhat.com>
Date:	Thu, 25 Feb 2010 18:42:41 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Wu Fengguang <fengguang.wu@...el.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Jens Axboe <jens.axboe@...cle.com>,
	Nick Piggin <npiggin@...e.de>,
	Chris Mason <chris.mason@...cle.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Clemens Ladisch <clemens@...isch.de>,
	Olivier Galibert <galibert@...ox.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	Christian Ehrhardt <ehrhardt@...ux.vnet.ibm.com>,
	Matt Mackall <mpm@...enic.com>,
	Linux Memory Management List <linux-mm@...ck.org>,
	linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 14/15] readahead: reduce MMAP_LOTSAMISS for mmap read-around

On 02/23/2010 10:10 PM, Wu Fengguang wrote:
> Now that we lifts readahead size from 128KB to 512KB,
> the MMAP_LOTSAMISS shall be shrinked accordingly.
>
> We shrink it a bit more, so that for sparse random access patterns,
> only 10*512KB or ~5MB memory will be wasted, instead of the previous
> 100*128KB or ~12MB. The new threshold "10" is still big enough to avoid
> turning off read-around for typical executable/lib page faults.
>
> CC: Nick Piggin<npiggin@...e.de>
> Signed-off-by: Wu Fengguang<fengguang.wu@...el.com>

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