Re: [Xen-devel] IDE drives

[Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>]

> 
> I'm seeing quite slow IDE write performance on Xenolinux-1.2 
> Native linux writes at 30MB/s to an ext2 fs, and Xenolinux DOM0 gets
> about 2MB/s (this is not a virtual disk extent).   hdparm doesn't work
> under xenolinux, but that is only part of the problem.  Native linux
> writes at 6MB/s without any hdparm tuning.

Take a look at the boot messages -- I suspect Xen hasn't got a
proper driver for your IDE chipset and is falling back to PIO.

You could try porting the driver from Linux (which I expect will
be easy), or wait until the new IO stuff is ready.
 
> The SCSI hosts seem fine.  native linux writes to scsi at 36MB/s and
> xen at 28MB/s.

I'm surprised you're seeing such a drop. With our aacraid
PERC3/Di cards we see (MB/s):
xenolinux       Write 28.3      Read 46.7
linux           Write 29.2      Read 47.2

Are you sure you're using the same part of the disk? It could be
a driver version issue, but I find it surprising you're
seeing such a performance drop.


Cheers,
Ian


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