Re: [Xen-devel] Nowadays, does xen support multicore , such as cell or not?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

Short answer: I don't know if Xen will run on Cell at the moment, and I 
suspect it wouldn't support all the advanced features of Cell yet.  But on 
x86 multicore it should run OK.

Xen has always supported multiprocessor hardware on the host side.  I'm not 
sure whether old versions of Xen would recognise modern multicore processors 
(because I'm not entirely sure how they're present to the system software) 
but I expect it probably would.

Current versions of Xen run happily on multicore x86 systems.  Since Xen 3.0, 
PV guests can be SMP also so that can take advantage of multiple logical 
processors (but they're not aware of threads vs cores vs packages so they're 
not able to make more targetted process scheduling decisions or memory 
allocation decisions based on this information).  Since a later revision in 
the Xen 3 series, you can also run HVM guests in SMP mode.

Cell hardware is a different case for two reasons:
1) it's PPC based.  The PowerPC port of Xen is not as far along as the x86 
port.  I don't know if the PPC port has been adapted for Cell yet, the last I 
heard they were currently concentrating on PPC970 chips.
2) it's not conventional multicore, because the SPUs are a different 
architecture to the PPC core and require separate management.  The hypervisor 
would have to acquire the ability to manage and swap SPU state across 
multiple virtual machines.  This is definitely doable, and I guess the IBM 
guys may look at it at some point.  But it's a different task to supporting 
SMP-style multipcore as is used on x86.

Hope that helps!

Cheers,
Mark



> I mean, does xen support hardware architecture such as cell ,or not?or
> does xen have plan for this support in the future?
>
> Thanks
>
> Steven Hu åé:
> > What do you mean?
> > The CPU virtualization in xen is unique VCPU, and when use the cpuid,
> > xen mask the multi-core return value. We can change the function
> > vmx_do_cpuid to cheat OS that the multi-vcpus is multi-vcore.
> >
> > 2007/11/8, tgh <wwwwww4187@xxxxxxxxxxx>:
> >> hi
> >>    Nowadays,does xen support multicore ,such as cell or others?or does
> >> xen plan to support it in the future?
> >>
> >> Thanks in advance
> >>
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> >
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-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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