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Date: Tue, 13 Nov 2001 14:18:42 -0200 (BRST)
From: Marcelo Tosatti <marcelo@conectiva.com.br>
To: "Craig I. Hagan" <hagan@cih.com>
Cc: Roy Sigurd Karlsbakk <roy@karlsbakk.net>, linux-kernel@vger.kernel.org,
        lars.nakkerud@compaq.com
Subject: Re: Tuning Linux for high-speed disk subsystems
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On Tue, 13 Nov 2001, Craig I. Hagan wrote:

> > After some testing at Compaq's lab in Oslo, I've come to the conclusion
> > that Linux cannot scale higher than about 30-40MB/sec in or out of a
> > hardware or software RAID-0 set with several stripe/chunk sizes tried out.
> > The set is based on 5 18GB 10k disks running SCSI-3 (160MBps) alone on a
> > 32bit/33MHz PCI bus.
> 
> this isn't quite true. use either the RH kernel, the -ac series, or the
> attached patch (for 2.4.15-pre4). Then set /proc/sys/vm/max-readahead to 511 or
> 1023 (power of 2 minus 1)
> 
> this should allow you to generate large enough io's for streaming reads to do
> what you are looking for.

Craig,

This patch is already on my pending list. 

So if Linus does not apply it, I will.

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