Date: Sat, 26 Nov 2005 14:25:24 +0100
From: Tomasz Torcz <zdzichu@irc.pl>
To: Wu Fengguang <wfg@mail.ustc.edu.cn>, Diego Calleja <diegocg@gmail.com>,
       linux-kernel@vger.kernel.org, akpm@osdl.org
Subject: Re: [PATCH 00/19] Adaptive read-ahead V8
Message-ID: <20051126132524.GA12396@irc.pl>
Mail-Followup-To: Wu Fengguang <wfg@mail.ustc.edu.cn>,
	Diego Calleja <diegocg@gmail.com>, linux-kernel@vger.kernel.org,
	akpm@osdl.org
References: <20051125151210.993109000@localhost.localdomain> <20051125164317.c42c0639.diegocg@gmail.com> <20051126031755.GA7226@mail.ustc.edu.cn>
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On Sat, Nov 26, 2005 at 11:17:55AM +0800, Wu Fengguang wrote:
> On Fri, Nov 25, 2005 at 04:43:17PM +0100, Diego Calleja wrote:
> > Recently, a openoffice hacker wrote in his blog that the kernel was
> > culprit of applications not starting as fast as in other systems.
> > Most of the reasons he gave were wrong, but there was a interesting
> > one: When you start your system, you've lots of free memory. Since
> > you have lots of memory, he said it was reasonable to expect that
> > kernel would readahead *heavily* everything it can to fill that
> > memory as soon as possible (hoping that what you readahead'ed was
> > part of the kde/gnome/openoffice libraries etc) and go back to the
> > normal behaviour when your free memory is used by caches etc.
> > "Teorically" it looks like a nice heuristic for desktops. Does
> > adaptative readahead does something like this?
>=20
> It's interesting ;)
> In fact some distributions do have a read-ahead script to preload files on
> startup. The readahead system call should be enough for this purpose:
>=20
> NAME
>        readahead - perform file readahead into page cache

posix_fadvise() with        POSIX_FADV_WILLNEED hint?
              The specified data will be accessed in the near future.

--=20
Tomasz Torcz                 Morality must always be based on practicality.
zdzichu@irc.-nie.spam-.pl                -- Baron Vladimir Harkonnen


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