Message-Id: <200401081430.i08EUVfx005021@turing-police.cc.vt.edu>
To: bert hubert <ahu@ds9a.nl>
Cc: axboe@suse.de, linux-kernel@vger.kernel.org
Subject: Re: blockfile access patterns logging 
In-Reply-To: Your message of "Thu, 08 Jan 2004 13:00:08 +0100."
             <20040108120008.GA7415@outpost.ds9a.nl> 
From: Valdis.Kletnieks@vt.edu
References: <20040108120008.GA7415@outpost.ds9a.nl>
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On Thu, 08 Jan 2004 13:00:08 +0100, bert hubert said:

> For some time I've wanted to log exactly what linux is reading and writing
> from my harddisk - for a variety of reasons. The current reason is that my
> very idle laptop writes to disk every once in a while (or reads, I don't
> know).
> 
> Now, conceptually this should not be very hard, but I'd like to ask your
> thoughts on where I might insert some crude logging? There are lots of
> places that might be better or worse for some reason.
> 
> I'd love to be as close to the physical block device as possible, short of
> rewriting actual IDE drivers.

You probably want to do logging at a higher level.  It's totally useless to find out
that LBA 2234324567 got re-written.  Mapping it to a partition on the disk so
you know it was something on /dev/hda7 is a bit better.  And being able to tell
that somebody updated the atime on /var/log/messages is most informative of all.

The other problem is that unless your laptop is *VERY* idle, you will have a scrolling
problem and buffering issues - so you end up writing to disk to log the buffers and... ;)

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