Subject: Re: Request: I/O request recording
From: Arjan van de Ven <arjanv@redhat.com>
Reply-To: arjanv@redhat.com
To: Felix von Leitner <felix-kernel@fefe.de>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <20040124181026.GA22100@codeblau.de>
References: <20040124181026.GA22100@codeblau.de>
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Organization: Red Hat, Inc.
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Date: Sat, 24 Jan 2004 19:26:17 +0100
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On Sat, 2004-01-24 at 19:10, Felix von Leitner wrote:
> I would like to have a user space program that I could run while I cold
> start KDE.  The program would then record which I/O pages were read in
> which order.  The output of that program could then be used to pre-cache
> all those pages, but in an order that reduces disk head movement.
> Demand Loading unfortunately produces lots of random page I/O scattered
> all over the disk.

I recently did something like this (and it scared me, it seems a typical
Fedora boot into gnome opens like 11.000 files ;) but via a printk in
the kernel....

I experimented with readahead'ing all that stuff while the initscripts
ran in the hope it would save time... but it doesn't somehow.

Some other things kinda help; if you feel adventurous you could play
with the kernel-utils RPM in rawhide which does a readahead of the files
the desktop opens while GDM login window is displayed; if the user isn't
typing his name really fast that decreases the desktop startup time...

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