On 11/08/2010 08:29 PM, Andrew Cathrow wrote:
> ----- Original Message -----
>> From: "Dennis Jacobfeuerborn"<denni...@conversis.de>
>> To: "Andrew Cathrow"<acath...@redhat.com>
>> Cc: "Bill Davidsen"<david...@tmr.com>, xen@lists.fedoraproject.org, 
>> v...@lists.fedoraproject.org, "M A Young"
>> <m.a.yo...@durham.ac.uk>
>> Sent: Monday, November 8, 2010 1:59:54 PM
>> Subject: Re: [fedora-virt] [Fedora-xen] Dom0 xen support in Fedora 15?
>> On 11/08/2010 06:02 PM, Andrew Cathrow wrote:
>>> ----- Original Message -----
>>>> From: "Bill Davidsen"<david...@tmr.com>
>>>> To: dl...@redhat.com
>>>> Cc: xen@lists.fedoraproject.org, v...@lists.fedoraproject.org, "M A
>>>> Young"<m.a.yo...@durham.ac.uk>
>>>> Sent: Monday, November 8, 2010 11:52:08 AM
>>>> Subject: Re: [fedora-virt] [Fedora-xen] Dom0 xen support in Fedora
>>>> 15?
>>>> Dor Laor wrote:
>>>>> On 11/08/2010 04:55 AM, M A Young wrote:
>>>>>> I am trying to work out whether it is practical to propose Dom0
>>>>>> xen
>>>>>> support as a feature for Fedora 15.
>>>>>> The kernel situation is that Domain 0 has been accepted upstream
>>>>>> for
>>>>>> 2.6.37. Assuming a 3 month kernel release cycle, F15 will most
>>>>>> likely ship
>>>>>> with a 2.6.37.x kernel, with 2.6.38 coming out either after the
>>>>>> F15
>>>>>> release or just before but too late to be included. If the plan
>>>>>> to
>>>>>> get key
>>>>>> xen drivers into 2.6.38 succeeds, then F15 may be become usable
>>>>>> as
>>>>>> a
>>>>>> Domain 0 system at some point during its lifetime as the kernel
>>>>>> package in
>>>>>> a Fedora version typically has one major update.
>>>>>> If the kernel team accept backported patches then it might just
>>>>>> be
>>>>>> possible to ship F15 with usable Domain 0 support but the
>>>>>> timescale
>>>>>> for
>>>>>> that would be very tight.
>>>>>> The other thing we would need to consider is what needs to be
>>>>>> done
>>>>>> to make
>>>>>> xen friendly enough to be usable by an ordinary user. The page
>>>>>> https://fedoraproject.org/wiki/Features/XenPvopsDom0 contains
>>>>>> plans
>>>>>> from
>>>>>> when dom0 xen support was expected to make a quick return to
>>>>>> Fedora, but
>>>>>> they are a couple of years old now so probably need updating.
>>>>>> I think as a minimum we would need a way to add a dom0 enabled
>>>>>> grub
>>>>>> entry
>>>>>> for a kernel, rather than requiring the user to hand edit the
>>>>>> grub
>>>>>> file.
>>>>>> We should also make sure that xen works with the other Fedora
>>>>>> virtualisation tools.
>>>>>> What do others think about this? For example is it achievable as
>>>>>> a
>>>>>> feature, is it too early and better to wait for F16, and what
>>>>>> else
>>>>>> should
>>>>>> we aim to do to make xen usable in Fedora?
>>>>> Have you consider kvm? it's upstream since 2.6.20 and now its more
>>>>> ready
>>>>> than ever.
>>>> There are some good tutorials which should explain the difference
>>>> between xen and kvm, particularly the performance and hardware
>>>> requirements of each.
>>> re: hardware requirements, KVM's requirement for VT-X/AMD-V
>>> extensions certainly used to be a concern 2-3 years ago but today
>>> even laptops come with this support.
>>> And regarding performance they days of Xen outperforming KVM have
>>> long-since passed.
>> Citations needed. I'm not saying what you claim isn't true but without
>> data
>> this opinion doesn't carry much weight.
> Citations are really needed on both sides of the debate, 2 or 3 year old 
> metrics no longer apply.

Which is why I hoped I could nudge you into providing some data if you had 
any. :)
There seems to be very little recent and hard data on the subject out there.

> Vendors published benchmarks are typically questionable, they focus on their 
> products strengths and their competitors weakness.
> The only hope for a fair comparison is a vendor neutral set of benchmarks 
> such as SPECvirt  http://www.spec.org/virt_sc2010/
> But obviously this isn't a simple test to run.

AFAIK there are some issues with that benchmark not being free.

What I'm basically looking for is a simple comparison of a few key metrics 
between common setups. For example a simple bonnie++ run on XenPV and 
KVM+virtio_blk could already give people at least some baseline numbers.

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