[Qemu-devel] Hyperthreading in the VM host

[Qemu-devel] Hyperthreading in the VM host

[Julian Chesterfield]

Hello, I'm still familiarising myself with the Qemu application and code, 
so apologies if this query has already been addressed or is 
inappropriate here! 

My understanding is that Qemu does not support hyperthreading in the host 
OS. I'm wondering what the arguments are for and against such support. Is it 
in fact architecturally feasible and could there potentially be any performance 
gain?

Thanks!
Julian

[Qemu-devel] Re: Hyperthreading in the VM host

[Ben Pfaff]

Julian Chesterfield <julian@thechesterfields.org> writes:

> My understanding is that Qemu does not support hyperthreading in the host 
> OS. I'm wondering what the arguments are for and against such support. Is it 
> in fact architecturally feasible and could there potentially be any performance 
> gain?

Why do you think qemu does not support a hyperthreaded host?  I
have no reason to believe that it does not, and I am curious why
you think otherwise.
-- 
Ben Pfaff 
email: blp@cs.stanford.edu
web: http://benpfaff.org

Re: [Qemu-devel] Hyperthreading in the VM host

[Jim C. Brown]

On Fri, Jan 21, 2005 at 03:52:43PM +0000, Julian Chesterfield wrote:
> My understanding is that Qemu does not support hyperthreading in the host 
> OS.

You mean guest OS, right? It shouldn't make a different if the host OS uses it
or not.

> I'm wondering what the arguments are for and against such support. Is it 
> in fact architecturally feasible and could there potentially be any performance 
> gain?

It would be easier to implement true SMP emulation inside of qemu. Hyperthreading
is just a way to make one CPU look like 2, so it is a way for the PIV to emulate
SMP... there is no point in emulating hyperthreading if we can implement SMP
inside of qemu. Why go to the trouble of getting one emulated cpu to do the
job of 2 when you can just emulate 2 cpus?

> 
> Thanks!
> Julian
> 
> 
> 
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