Re: multi-core VMM

ZHANG Zhi
Thu, 10 Jan 2013 13:00:38 -0000

Yeah, I think you''re right.
	Maybe it also depends on the virtualization techniques. If it''s
hardware assisted virtualization, guest OS may detect the HT info, because it
can also scan the BIOS memory, right?


re: Re: [Xen-devel] multi-core VMM

Well, I can''t agree.
HW provide features and SW use it. Otherwise, HW feature is just a vain.

PS: please keep the list CCed so that people are aware of the discussion.
Probably they have something to share on this topic.

On Wed, Jan 9, 2013 at 1:37 PM, ZHANG Zhi <zhizhang@smu.edu.sg>
wrote:
> I think it''s the hardware''s business, namely the Intel or
AMD, not the hyperviosr''s business. Xen does not have to consider such
an issue.
>
> Re:
> I think that''s possible, you can check the cpupool related command
in the xl manpage.
>
> But I have a similar question -- In CPU like i7, 8 logical cores are not
fully equivalent.
> They are hyper-threading over CMP. The two HT cores from a single physical
core are contending for pipeline resource. In linux kernel, there is specific
scheduler optimization for this case.
> My question is that how XEN hypervisor handle this? Will such HT info be
available to the VM?
> I guess there may be some different depend on whether you bind VCPU to host
core or not.
>
> Also, is there any different for dom0 && domU in this aspect?
>
> Thanks,
> Timothy
>
> On Wed, Dec 19, 2012 at 2:20 PM, ZHANG Zhi <zhizhang@smu.edu.sg>
wrote:
>> Hi, list,
>>
>> A VMM provides a VMCS for each VM. How does the VMM assign system
>> resources for each VM? For example, in a multi-core environment, how
>> can I enable the VMM to run, say, on a two-core intel''s
processor
>> while I am able to force a VM to execute only on a specific core upon
>> initializing the Guest OS ? that is to say, how I can assure the VM
>> to believe that there is only one physical core running on this
machine?
>>
>> What should I do? Is it possible to assign a core when VMM starts a
>> new VM after the VMM is booted ?
>>
>>    Thanks a lot!
>>
>>
>>
>>
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>>