[Xen-users] Re: xen 2.0.7 on SuSE 9.3 very slow responses in dom0

[Dirk Estreng <dirk.estreng@xxxxxx>]

Joost Roeleveld <joost <at> roeleveld.co.uk> writes:

> 
> On Jan 03, 2006 02:56 PM, Dirk Estreng <dirk.estreng <at> gmx.de> wrote:
> 
> >Tracked it down a little more:
> >
> 
> <snipped analysis>
> 
> >
> >So as far as i understand my ATA drive locks up my CPU...
> >Where is the problem??
> >
> >I am running:
> >xen2.0.7 on suse 9.3 with 2.6.11.4-21.8-xen
> 
> Hi Dirk,
> 
> I'm not yet familiar with Xen, subscribed to the list to get some
> pointers while waiting for the new computer to arrive.
> I have seen a similar problem with a 'normal' linux install though.
> Do you have DMA enabled?
> Use hdparm to check this, not sure which flags to use, can't check at
> the moment.
> 
> Without DMA, the performance of harddrives are really bad and can cause
> very high CPU utilisation.
> 
> If you can't enable DMA (using hdparm), you will need to load the
> correct IDE-driver for your system, lspci should be able to tell you
> which chipset you are using and then you need to configure the correct
> IDE driver into the kernel.
> You might need to disable the generic driver to avoid it claiming the
> device before the proper driver gets to it.
> 
> Hope this helps.
> 
> Kind regards,
> 
> Joost
> 

Hi Joost,

thanks for your reply and help! I think it was indeed a problem with the chipset
of my test machine (SiS). The onboard IDE controller seems not to work correctly
(in DMA mode) with my XEN kernel. I completely overlooked this fact because
without XEN it was running fast and afaik hdparm said the drive was using UDMA
(in fact this was one of the first things that came up my mind)...

BUT it seems the drive WAS running in slow PIO mode. 

Now it works ;-)

thanks
dirk






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