linux-kernel - Re: [PATCH 2/3] vmscan: make mapped executable pages the first class citizen

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Date:	Tue, 19 May 2009 14:27:58 +0800
From:	Wu Fengguang <fengguang.wu@...el.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	Christoph Lameter <cl@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Elladan <elladan@...imo.com>, Nick Piggin <npiggin@...e.de>,
	Johannes Weiner <hannes@...xchg.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Rik van Riel <riel@...hat.com>,
	"tytso@....edu" <tytso@....edu>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"minchan.kim@...il.com" <minchan.kim@...il.com>
Subject: Re: [PATCH 2/3] vmscan: make mapped executable pages the first
	class citizen

On Tue, May 19, 2009 at 01:09:32PM +0800, Wu Fengguang wrote:
> On Tue, May 19, 2009 at 12:41:38PM +0800, KOSAKI Motohiro wrote:

> Note that I was creating the sparse file in btrfs, which happens to be
> very slow in sparse file reading:
> 
>         151.194384MB/s 284.198252s 100001x 450560b --load pattern-hot-10 --play /b/sparse
> 
> In that case, the inactive list is rotated at the speed of 250MB/s,
> so a full scan of which takes about 3.5 seconds, while a full scan
> of active file list takes about 77 seconds.

Hi KOSAKI: you can limit the read speed with iotrace.rb's
"--think-time" option, or to read the sparse file over network.

Thanks,
Fengguang
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