Re: [Xen-users] poor IDE buffered disk reads on dom0

To:	Anand <xen.mails@xxxxxxxxx>
Subject:	Re: [Xen-users] poor IDE buffered disk reads on dom0
From:	Chris Fanning <christopher.fanning@xxxxxxxxx>
Date:	Wed, 25 Jan 2006 16:05:36 +0100
Cc:	xen-users@xxxxxxxxxxxxxxxxxxx
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On 1/25/06, Anand <xen.mails@xxxxxxxxx> wrote:
> On 1/25/06, Chris Fanning <christopher.fanning@xxxxxxxxx> wrote:
> > I have a question about disk access. (IDE in my case)
> >
> > When I _don't_ boot the xen dom0 kernel and run hdparm -tT
> > Timing buffered disk reads: 156 MB in 3.03 seconds = 51.44 MB/sec
> >
> > When I boot xen dom0 and run hdparm -tT
> > Timing buffered disk reads: 8 MB in 3.22 seconds = 2.48 MB/sec
> >
> > I'm running this on debian testing and compiling xen3.0.0
> >
> > When booting dom0 I get those fatal errors of the type "ide_generic
> > module not found" (i've seen those on other instalations). While
> > compiling xen from the source I noticed that ide_generic.o (i think)
> > isn't compiled as a module.
>
> Which kernel are you compiling ? linux-2.6-xen0 / linux-2.6-xen
>  Ian recommends using the xen kernel since it packs in more drivers, so if
> you aren't using that, try to compile that and use it.
Can you point me to a link on that?

my install procedure simply:

wget ..../downloads/xen-3.0.0-src.tgz
tar -xvzf xen-3.0.0-src.tgz
cd xen-unstable
make world
make install
sh ./install.sh

/boot/grub/menu.lst
title   Xen 3.0.0 / XenLinux 2.6.12.6-xen0
root    (hd0,0)
kernel  /xen.gz dom0_mem=128M
module  /vmlinuz-2.6.12.6-xen0 root=/dev/hda6 ro console=tty0

Thanks
Chris.

> > I'm a bit stuck. Sould I compile ide as a module for dom0?
> > Or perhaps this isn't even the problem?
> > Should I forget about IDE and go and buy SATA?
> >
>
> As for SATA, it definately gives you more performance ;)
>
> --
>
> regards,
>
> Anand

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