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Date: Tue, 16 Apr 2002 13:40:49 -0300 (BRT)
From: Rik van Riel <riel@conectiva.com.br>
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To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Andrea Arcangeli <andrea@suse.de>,
        Moritz Franosch <jfranosc@physik.tu-muenchen.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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On Tue, 16 Apr 2002, Alan Cox wrote:

> > > benchmarks 1-4, kernel 2.4.19-pre5 performed much worse than
> > > 2.4.18. The reason may be that the main throughput stems from the
> > > short moments where, for what reason whatsoever, read speed increases
>
> Fairness, throughput, latency - pick any two..

Personally I try to go for fairness and latency in -rmap,
since most real workloads I've encountered don't seem to
have throughput problems.

The standard "it's getting slow" complaint has been about
response time and fairness 90% of the time, usually when
the system stalls one process during some other activity.

> > Right fix is different but not suitable for 2.4.
>
> Curious - what do you think the right fix is ?

Tuning the current system for latency and fairness should
keep most people happy. Desktop users really won't notice
if unpacking an RPM takes 20% longer, but having their
mp3 skip during RPM unpacking is generally considered
unacceptable.

regards,

Rik
-- 
	http://www.linuxsymposium.org/2002/
"You're one of those condescending OLS attendants"
"Here's a nickle kid.  Go buy yourself a real t-shirt"

http://www.surriel.com/		http://distro.conectiva.com/

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