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Date: Thu, 05 Sep 2002 12:02:59 -0700
From: Andrew Morton <akpm@zip.com.au>
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To: Kianusch Sayah Karadji <kianusch@sk-tech.net>
CC: linux-kernel@vger.kernel.org
Subject: Re: tuning/turning off disc caching?
References: <Pine.LNX.4.43.0209051929160.2388-100000@merlin>
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Kianusch Sayah Karadji wrote:
> 
> Hi!
> 
> Is there a way tuning (down) or turning off the disc caching in Linux for
> certain devices?
> 
> What I do is writing data via dd or mkisofs directly to a DVD-RAM
> (/dev/srX).  The kernel sees the DVD-RAM as a hard-disc.  It works fine.
> The Problem is that during the write operation (which takes some time for
> 4,7GB data).  The system slows down extremely and all the memory is used
> for caching.
> 

There are no very good solutions to this at present.  The following should
help:

- Drastically decrease the dirty memory thresholds in /proc/sys/vm/bdflush

- Make the writing application run fsync(fd) every few megabytes.

- Run /bin/sync once per second.
-
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