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RE: Réf. : [Xen-ia64-devel] Time for hybridvirtualization?

To: <jean-paul.pigache@xxxxxxxx>, "Alex Williamson" <alex.williamson@xxxxxx>
Subject: RE: Réf. : [Xen-ia64-devel] Time for hybridvirtualization?
From: "Xu, Anthony" <anthony.xu@xxxxxxxxx>
Date: Thu, 17 Jan 2008 21:42:53 +0800
Cc: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx, xen-ia64-devel <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: Réf. : [Xen-ia64-devel] Time for hybridvirtualization?
following is my thinking, it may be wrong.
If we want to run dom0 on VTi, we still need to support of paravitualization, madison is still being used.
We can have two branch, one VT-i dom0, the other is para dom0.
We may focus on VT-i dom0 branch.
While we still support para dom0, if there are bugs, we need to fix it, but we will not update xenolinux to new release version, we just try to make all functions work well.
In the other side, It's impossible Redhat would like to maintain two modified linux version, one is for hybrid, the other is for para.
Redhat may choose modified linux version for hybrid, it is more easier for maintain.
- Anthony

From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of jean-paul.pigache@xxxxxxxx
Sent: 2008年1月17日 19:05
To: Alex Williamson
Cc: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx; xen-ia64-devel
Subject: Réf. : [Xen-ia64-devel] Time for hybridvirtualization?

Alex and all,

we, in Bull,  are using Xen-ia64 to provide logical partitioning for Linux physical partitions in our mainframe systems running on Itanium.
Some of these systems have been delivered with Madison CPUs which are non-VT.
So I would vote for keeping the support of paravirtualization.

On the technical side, I agree with the long-term objective, but performance is a major point and I think we should not discard paravirtualization until we have verified that there is no performance regression with most of the CPUs installed in Itanium systems.
Knowing that performance will be better with Tukwila is a valuable information for a long term objective but Tukwila is not what is installed to-day.
So my opinion is that removing paravirtualization may be a good choice for the long term, but deciding to do it now is premature.

Best regards

Alex Williamson <alex.williamson@xxxxxx>
Envoyé par : xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx

17/01/2008 01:02

        Pour :        xen-ia64-devel <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
        cc :        
        Objet :        [Xen-ia64-devel] Time for hybrid virtualization?

  Is it possible?  Is it a good idea?  What are some of the issues?  We
would lose support for non-VT capable processors (pre-Montecito), but is
that so bad?  Is it a "fast track" to upstream Linux Xen/ia64 support?
Let me know your thoughts.  Thanks,


[1] http://ols.108.redhat.com/2007/Reprints/nakajima-Reprint.pdf

Alex Williamson                             HP Open Source & Linux Org.

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