linux-kernel - Re: [RFC] mmaped copy too slow?

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Message-Id: <20080116110200.11B4.KOSAKI.MOTOHIRO@jp.fujitsu.com>
Date:	Wed, 16 Jan 2008 11:05:09 +0900
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Paulo Marques <pmarques@...popie.com>
Cc:	kosaki.motohiro@...fujitsu.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC] mmaped copy too slow?

Hi Paulo

> One thing you could also try is to pass MAP_POPULATE to mmap so that the 
> page tables are filled in at the time of the mmap, avoiding a lot of 
> page faults later.
> 
> Just my 2 cents,

OK, I will test your idea and report about tomorrow.
but I don't think page fault is major performance impact.

may be, below 2 things too big
  - stupid page reclaim
  - large cache pollution by memcpy.

Just my 2 cents :-p


- kosaki


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