Re: hyperthreading or not

[Jo Shields <jo.shields@comlab.ox.ac.uk>]

Emmanuel Fleury wrote:

> Jo Shields wrote:
>  
>
> > The problem with hyperthreading is that there's only a bare minimum of
> > distinct hardware - almost all resources are shared. notably, a pipeline
> > stall on one thread (where the pipelines on a p4 are ridiculously long)
> > will flufh the hyperthread's pipeline too.
> >    
>
> Ok, two threads in the same time means that you double your chance of
> pipeline stall. It must be killing yourself on a P4, but what about an
> AMD64 ?
>
> The depth of the pipeline is still reasonable (isn't it ?).
>
> Regards
>  
There's no HT on AMD chips, so it's a non-issue; and on dual-core chips 
(either Intel or AMD) the cores are distinct, so flushes happen separately