Re: [Xen-devel] Question about hyper-threading of domains

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 29 Apr 2005, at 20:42, Jacob Gorm Hansen wrote:

> is it possible, and will it make sense, to allow an SMP-domain access 
> to both SMT/Hyper threads of a CPU?
> My performance measurements of the small address spaces implementation 
> (SAS) seem to indicate that having the driver domain in a separate 
> hyper thread is still a little faster than SAS for a non-SMP/SMT domU. 
>  I guess that means that that SMT IPIs are about the same cost as ring 
> switches.
HT is designed to look almost identical to SMP, so it is no problem to 
give both HTs to a multi-processor domain. This will make sense if the 
domain is running a workload that benefits from HT (e.g., probably 
certain types of multi-threaded application).
In most cases I expect it will give better overall performance to 
allocate the second HT solely to a driver domain.
 -- Keir


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