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To: Rik van Riel <riel@conectiva.com.br>
Cc: Andrea Arcangeli <andrea@suse.de>, <marcelo@conectiva.com.br>,
        <linux-kernel@vger.kernel.org>
Subject: Re: IO performance problems in 2.4.19-pre5 when writing to DVD-RAM/ZIP/MO
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From: Moritz Franosch <jfranosc@physik.tu-muenchen.de>
Date: 17 Apr 2002 17:35:53 +0200
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> Judging from the performance regression above it would seem the
> new defaults suck rocks.

I first thought that 2.4.19-pre5 would be better than 2.4.18 because
vmstat showed that 2.4.19-pre5 could still read 1-2 MB per second from
HDD while writing to DVD-RAM, whereas 2.4.18 blocked totally for more
than 10 seconds or so. But there are short moments under both kernels
(with default bdflush parameters) where you get data from HDD at a
very high rate before it drops again. It seems the main throughput
over a long time stems from these short moments.


> Can we please stop optimising Linux for a single workload benchmark
> and start tuning it for the common case of running multiple kinds
> of applications and making sure one application can't mess up the
> others ?
> 
> Personally I couldn't care less if my tar went 30% faster if it
> meant having my desktop unresponsive for the whole time.

That's why I did the benchmarks in the first place, because my desktop
was unresponsive while writing to DVD-RAM.


Moritz


-- 
Dipl.-Phys. Moritz Franosch
http://Franosch.org
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