Message-ID: <40E1FDEC.6020606@techsource.com>
Date: Tue, 29 Jun 2004 19:40:28 -0400
From: Timothy Miller <miller@techsource.com>
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To: Markus Schaber <schabios@logi-track.com>
CC: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Block Device Caching
References: <20040630002014.4970b82d@kingfisher.intern.logi-track.com>
In-Reply-To: <20040630002014.4970b82d@kingfisher.intern.logi-track.com>
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Markus Schaber wrote:

> This lead us to the conclusion that block devices do not cache, but the
> filesystem does. But subsequently, I ran some tests on my developer
> machine (Pentium 4 Mobile Laptop).


I had kernel experts repeatedly insist to me that block devices were 
cached, while all of my tests (using dd to or from, say, /dev/sda1 or 
whatever) indicated that there was absolutely no caching whatsoever.

In my experience, reads and writes to block devices are uncached, while 
filesystem stuff IS cached.

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