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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>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Will Xen 4.0 release use the pv-ops kernel despite it's performance hit
From: "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx>
Date: Mon, 21 Dec 2009 14:39:49 +0800
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Thread-topic: [Xen-devel] Will Xen 4.0 release use the pv-ops kernel despite it's performance hit
Tom Rotenberg wrote:
> OK.
> 
> I just thought i saw Jeremy's mail about changing the APIC logic in
> Xen to conform to the pv-ops kernel, which i thought will cause new
> Xen not to work with old dom0 kernel. This isn't the case?

As I know, new Xen should work with old dom0 after APIC logic changes, but new 
dom0 may not be able to run on old Xen. To make new dom0 work with old Xen 
hypervisor, has to backport two small patches Cset#20491 and Cset20509.  
Keir, 
   Do you think we should backport them to Xen3.4-testing tree ? Since logic 
has no any change, and just added a new hypercall, I think they should be good 
to xen-3.4-testing tree ?  :)
Xiantao

> On Sun, Dec 20, 2009 at 11:53 PM, Keir Fraser
> <keir.fraser@xxxxxxxxxxxxx> wrote: 
>> On 20/12/2009 17:41, "Tom Rotenberg" <tom.rotenberg@xxxxxxxxx> wrote:
>> 
>>> 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
>>> version, will just cause people not to upgrade to Xen 4.0
>>> (especially 
>>> if Xen 4.0, won't support the old 2.6.18 xen kernel anymore).
>>> 
>>> Is this performance issue going to be addressed prior to Xen 4.0
>>> release? 
>> 
>> Work on both stabilisation and performance will be ongoing. But bear
>> in mind that upgrading to Xen 4.0 will not require users to switch
>> to pv_ops dom0. 
>> 
>>  -- Keir
>> 
>> 
>> 
> 
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