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* What are the rules for hyperthreaded CPUs?
@ 2011-12-05  0:41 Todd And Margo Chester
  0 siblings, 0 replies; 3+ messages in thread
From: Todd And Margo Chester @ 2011-12-05  0:41 UTC (permalink / raw)
  To: kvm

Hi All,

My host has an i7-960 processor (4 cores, 8 hypterthreaded cores.)
/proc/cpuinfo on my host shows 8 processors.

On my Fedora Core 16 guest, /proc/cpuinfo shows 4 processors.

Question: what is the maximum number of processors I can assign to my
guest?  4 or 8?  What are the rules for Hyperthreading?

Many thanks,
-T

^ permalink raw reply	[flat|nested] 3+ messages in thread

* What are the rules for hyperthreaded CPUs?
@ 2011-12-05  1:26 Todd And Margo Chester
  2011-12-05  7:42 ` Michael Tokarev
  0 siblings, 1 reply; 3+ messages in thread
From: Todd And Margo Chester @ 2011-12-05  1:26 UTC (permalink / raw)
  To: kvm

> Hi All,
>
> My host has an i7-960 processor (4 cores, 8 hypterthreaded cores.)
> /proc/cpuinfo on my host shows 8 processors.
>
> On my Fedora Core 16 guest, /proc/cpuinfo shows 4 processors.
>
> Question: what is the maximum number of processors I can assign to my
> guest?  4 or 8?  What are the rules for Hyperthreading?
>
> Many thanks,
> -T

Figured it out.  The max cores is the number of hyperthreaded cores
(eight in my case).

My mistake was that in virt-manager, processor, I was not clicking
on "Copy host CPU configuration" button.  Without that, everything
I tried to configure came out as single CPUs.

-T

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: What are the rules for hyperthreaded CPUs?
  2011-12-05  1:26 Todd And Margo Chester
@ 2011-12-05  7:42 ` Michael Tokarev
  0 siblings, 0 replies; 3+ messages in thread
From: Michael Tokarev @ 2011-12-05  7:42 UTC (permalink / raw)
  To: Todd And Margo Chester; +Cc: kvm

On 05.12.2011 05:26, Todd And Margo Chester wrote:
>> Hi All,
>>
>> My host has an i7-960 processor (4 cores, 8 hypterthreaded cores.)
>> /proc/cpuinfo on my host shows 8 processors.
>>
>> On my Fedora Core 16 guest, /proc/cpuinfo shows 4 processors.
>>
>> Question: what is the maximum number of processors I can assign to my
>> guest?  4 or 8?  What are the rules for Hyperthreading?
>>
>> Many thanks,
>> -T
> 
> Figured it out.  The max cores is the number of hyperthreaded cores
> (eight in my case).

The maximum number of guest vCPUs is unlimited - you can assign, say,
100 cores - each vCPU core is just a thread on host, it does not
correspond to any physical characteristics of your host.

/mjt

^ permalink raw reply	[flat|nested] 3+ messages in thread

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2011-12-05  1:26 Todd And Margo Chester
2011-12-05  7:42 ` Michael Tokarev

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