Xen users - May 2007 - What means "...up to 32-way SMP guest operating systems"

hi,

i writing a brand new howto in German, but i can''t translate the
sentence: ...up to 32-way SMP guest operating systems

What does it mean exactly?

cu denny



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hi,

Guillaume Lenoir schrieb:
> up to 32 Virtual CPUs in a VM I''d assume ? 
i assume it too, but does it mean, i need ''bout 32 "physical"
CPUs for
using them inside the VM, or can i "split" a single physical CPU into
32CPUs inside the VM?

cu denny



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> -----Original Message-----
> From: xen-users-bounces@lists.xensource.com 
> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of 
> Denny Schierz
> Sent: 03 May 2007 11:14
> To: ''xen-users@lists.xensource.com''
> Subject: Re: [Xen-users] What means "...up to 32-way SMP 
> guest operating systems"
> 
> hi,
> 
> Guillaume Lenoir schrieb:
> > up to 32 Virtual CPUs in a VM I''d assume ? 
> 
> i assume it too, but does it mean, i need ''bout 32
"physical" CPUs for
> using them inside the VM, or can i "split" a single physical CPU
into
> 32CPUs inside the VM?
You can in theory have 32 VCPU''s per domain, and you really only need a
single CPU to run say, 8 domains x 32 VCPUs -> 256 VCPUs. Of course,
this isn''t a very efficient way to do things. There are some
circumstances where you may want to have a guest run more than 1.0 VCPU
per PCPU (note that it''s a "non-integer" number, so you could
run 1.3333
VCPU''s per PCPU by having 4VCPU, 3PCPU), but that''s special
cases,
rather than the common scenario. 

Having a total count of VCPU''s > PCPU''s is quite common
however - in
server consolidation, this is exactly what you''re looking for.

Finally, the number of physical CPU''s Xen can handle is limited by the
bitsize of a "long", which is 32 for 32-bit builds of Xen, whilst in
theory it can be changed to 64 for a 64-bit build. And we''re talking
CPU
cores here, so with quad-core CPUs, you need 8 sockets to make a 32 CPU
machine. Not exactly the most common variety of motherboard/system. 

--
Mats
> 
> cu denny
> 
> 


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hi,

Petersson, Mats schrieb:
> You can in theory have 32 VCPU''s per domain, and you really only
need a
> single CPU to run say, 8 domains x 32 VCPUs -> 256 VCPUs. Of course,
> this isn''t a very efficient way to do things. There are some
big thanks for the explanation. My problem was to understand: why I want
to split a single core, into more virtual CPUs in a VM. But Server
consolidation with Installations on SMP make sense.

big thanks!

cu denny



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