Re: [Xen-devel] Report on Virtualization in Clusters - Håvard Bjerke - com.xensource.lists.xen-devel

7 messages in com.xensource.lists.xen-develRe: [Xen-devel] Report on Virtualizat...

From	Sent On	Attachments
Håvard Bjerke	25 Nov 2004 04:54
Jacob Gorm Hansen	26 Nov 2004 02:43
Håvard Bjerke	26 Nov 2004 05:32
Rune Johan Andresen	26 Nov 2004 07:26
Håvard Bjerke	26 Nov 2004 08:07
Ian Pratt	28 Nov 2004 03:16
Håvard Bjerke	28 Nov 2004 03:54

Subject:	Re: [Xen-devel] Report on Virtualization in Clusters
From:	Håvard Bjerke (hava...@idi.ntnu.no)
Date:	11/26/2004 05:32:03 AM
List:	com.xensource.lists.xen-devel

On Fri, Nov 26, 2004 at 11:44:03AM +0100, Jacob Gorm Hansen wrote:

Håvard Bjerke wrote:

Rune and I just finished writing a report on using virtualization with Xen in clusters, with focus on network performance. You may download it from http://www.idi.ntnu.no/~havarbj/clust_virt.pdf

We hope you find it interesting!

Yes, very interesting. Good work.

It seems from your tests without interrupt coalescing that Xen has a higher interrupt-handling overhead than native Linux. I suppose that with the new IO model, Xen needs to flush the TLBs for every interrupt that arrives. Do you think this is the reason for the overhead, or are the performance problems only due to your hardware being badly supported by Xen?

My guess is that it is the former, because we "solved" the problem with the
IOAPIC bug with 'ignorebiostables'. Thus using legacy PIC, everything seemed to
behave normally except when not using IC.

I think it boils down to whether or not using legacy PIC as opposed to (a
supported) IOAPIC has an impact on interrupt handling. If it does, I think it's
the latter reason, otherwise I think it's the former.

It would be quite easy to verify on the other cluster. I just couldn't find out
how to disable IC on the tg3 driver.

The Xen developers could probably give a better answer, though.

Håvard