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Date: Mon, 24 Feb 2003 13:53:23 -0800
From: Andrew Morton <akpm@digeo.com>
To: Patrick Mansfield <patmans@us.ibm.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: 2.5.62-mm2 slow file system writes across multiple disks
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Patrick Mansfield <patmans@us.ibm.com> wrote:
>
> Hi -
> 
> Running 2.5.62-mm2, I was trying to get multiple commands queued to
> different scsi disks via writes to multiple file systems (each fs
> on its own disk), but got rather low performance.
> 
> Are there any config options or settings I should change to improve the
> performance?
> 
> Is this expected behaviour for now?
> 
> I'm mounting 10 disks using ext2 with noatime, starting 10 dd's in
> parallel, with if=/dev/zero bs=128k count=1000, then umount-ing after each
> dd completes.

Could be that concurrent umount isn't a good way of getting scalable
writeout; I can't say that I've ever looked...

Could you try putting a `sync' in there somewhere?

Or even better, throw away dd and use write-and-fsync from ext3 CVS.  Give it
the -f flag to force an fsync against each file as it is closed.

http://www.zip.com.au/~akpm/linux/ext3/


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