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Re: [Xen-devel] Will Xen 4.0 release use the pv-ops kernel despite it's

To: Tom Rotenberg <tom.rotenberg@xxxxxxxxx>, jun.nakajima@xxxxxxxxx
Subject: Re: [Xen-devel] Will Xen 4.0 release use the pv-ops kernel despite it's performance hit
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Mon, 21 Dec 2009 09:59:57 -0500
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On Sun, Dec 20, 2009 at 07:41:31PM +0200, Tom Rotenberg wrote:
> Hi All,
> Will Xen 4.0 release use the pv-ops kernel, despite the fact that it
> has about ~15% hit in performance?
> This is a major performance hit, and releasing a new Xen version with
> a 15% performance hit in the dom0 kernel compared to a previous

I am quite curious about this. Earlier in November I asked about this and
was told the same issue - but no hard numbers. Recently Jun from Intel mentioned
that they had run performance numbers that they would share in Xen-conference 
in Asia
(wasn't there, bummer) and which would be posted on xen-devel (Jun: hint hint).

The numbers they listed was ~5% (this is 2.6.31 dom0 compared to 2.6.18 dom0).
Thought I don't remember if baremetal 2.6.31 vs baremetal 2.6.18 has the ~5% 
as well?

I don't have the hard numbers, and I haven't come to the stage where I can start
tracking this down, so I was wondering if somebody else in the community had
done this? And perhaps also run the right profiling tool to figure out where 
hit is happening?

> Is this performance issue going to be addressed prior to Xen 4.0 release?

I know that one of the issues for DomU was resolved a couple of months ago. But
besides that we are working on stabilizing the kernel first.

It goes without saying that any help in the performance department (especially
collecting profile data as this is happening) would be much appreciated.

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