xeon hyperthreading & GIL

[Seb Bacon]

Aahz wrote:
> In article <1044530966.192487 at ananke.eclipse.net.uk>,
> Seb Bacon  <seb.bacon at jamkit.com> wrote:
>>Can anyone give me the lowdown on how hyperthreading on the Xeon might 
>>effect python performance?
>>
>>AFAICT the cost of context switching is very low so the impact of 
>>releasing the GIL should be minimal.
> 
> 
> <shrug>  Consider hyperthreading as functionally equivalent to multiple
> CPUs; from Python's perspective, there's no difference.

Yes, I realise that; my question was about performance WRT scheduling in 
modern OSs & SMP/SMT systems, not about functionality in python.

Let me try again:

Currently python's global interpreter lock will often cause SMP system 
performance to *decrease* due to the cost of context switching.

Is the same true for SMT systems, or is context switching less of an 
issue due to shared cache, etc?

seb