RE: [Xen-devel] how many processors does xen support in hardware?

["Puthiyaparambil, Aravindh" <aravindh.puthiyaparambil@xxxxxxxxxx>]

It is not hard coded to 255. For example if you want to up the number to 96, 
then build Xen x86_64 with "make max_phys_cpus=96" and so on. But like I 
mentioned anything above 126 will require some patching.

BTW (echoing Keir's question), why do you think it is hard coded to 255?

Aravindh

-----Original Message-----
From: pradeep singh rautela [mailto:rautelap@xxxxxxxxx] 
Sent: Friday, August 24, 2007 10:33 AM
To: Puthiyaparambil, Aravindh
Cc: tgh; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] how many processors does xen support in hardware?

On 8/24/07, Puthiyaparambil, Aravindh
<aravindh.puthiyaparambil@xxxxxxxxxx> wrote:
> Xen x86_32/PAE supports 32 logical CPUs. This is a hard limit and there is no 
> easy way to increase this.
>
> Xen x86_64 supports 64 logical CPUs. You need to compile Xen with 
> max_phys_cpus=64 to enable this support. If you want to go beyond 126 LCPUs 
> some patching is needed.
>
> I guess you can theoretically go up to 255 but I think you might run out of 
> GDT slots before that.

Right, so why keep 255 there at all? I mean why hard code it  to a max
255 then?Put it at a number a little near or higher than what Xen is
actually capable of.

thanks
>
> Aravindh Puthiyaparambil
> Virtualization Engineer
> Virtual Systems Development
> Unisys, Tredyffrin PA
>
> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of tgh
> Sent: Friday, August 24, 2007 7:31 AM
> To: pradeep singh rautela
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] how many processors does xen support in hardware?
>
> pradeep singh rautela 写道:
> > On 8/24/07, tgh <tianguanhua@xxxxxxxxxx> wrote:
> >
> >> hi
> >>    how many processors does xen support in hardware for the practical
> >> system?
> >>
> >
> > Thats would be 255 i guess.
> >
> thank you for your reply
> but I want to kown the max number of hardware cpus the xen could
> support, or the xen's scalability in the aspect of cpu number,not in the
> aspect of the VM number
>
> thanks
>
>
>
>
>
> > thanks
> >
> >>   what is the max number of processors in the practice system running
> >> under xen ?
> >>
> >
> >
> >> Thanks in advance
> >>
> >>
> >> _______________________________________________
> >> Xen-devel mailing list
> >> Xen-devel@xxxxxxxxxxxxxxxxxxx
> >> http://lists.xensource.com/xen-devel
> >>
> >>
> >
> >
> >
>
>
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>


-- 
--
pradeep singh rautela

"Genius is 1% inspiration, and 99% perspiration" - not me :)

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