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Re: Strange system behaviour when copying disks

To: Olaf Frączyk <olaf@xxxxxxxxxxxxx>
Subject: Re: Strange system behaviour when copying disks
From: Steve Lord <lord@xxxxxxx>
Date: 14 May 2003 10:55:26 -0500
Cc: Walt H <waltabbyh@xxxxxxxxxxx>, linux-xfs@xxxxxxxxxxx
In-reply-to: <1052927449.6816.6.camel@venus>
References: <1052916810.2395.15.camel@venus> <3EC25EE0.5000007@xxxxxxxxxxx> <1052927449.6816.6.camel@venus>
Sender: linux-xfs-bounce@xxxxxxxxxxx
On Wed, 2003-05-14 at 10:50, Olaf Frączyk wrote:
> On Wed, 2003-05-14 at 17:21, Walt H wrote:
> > 
> > Do you have dma enabled on your IDE disks? I can't think of any reason
> > off the top of my head why a cat from hda -> hdc should be affected by
> > XFS, as you aren't using the filesystem for that - it's just reading the
> > raw device. 
> Yes, I know. I just don't know if XFS code changes some buffering etc.
> Maybe with vanilla kernel it would be the same. I just have no easy way
> to test it.
> Make sure dma is enabled on hda and hdc and see if that
> > helps:  hdparm -d1 /dev/hda /dev/hdc
> > 
> Both drives have dma enabled.
> And they are set to UDMA-100 also.
> I'm just curious where from comes this terrible latency.
> Regards,
> Olaf

XFS should not affect this in any way, I am sure the unmodified kernel
would behave the same way for you.



Steve Lord                                      voice: +1-651-683-3511
Principal Engineer, Filesystem Software         email: lord@xxxxxxx

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