[Ukfreebsd] Disabling hyperthreading on Intel CPUs

andy thomas andy at time-domain.co.uk
Wed Jan 26 09:44:27 GMT 2011

On Wed, 26 Jan 2011, Mark Blackman wrote:

> On Wed, 26 Jan 2011 09:33:12 -0000, andy thomas <andy at time-domain.co.uk> 
> wrote:
>> I want to disable HT because it can impact performance when used to execute 
>> code compiled for parallel execution across multiple PCs.
> So your code is so efficient at utilizing execution resources, (i.e. not 
> really ever stalling), that the HT overhead slows you down?

I suspect it is! So that's why we'd like to find out by running benchmarks 
over maybe 150 PCs but fiddling with the BIOS on this many machines is not 
an enjoyable use of my time. If it can't be disabled via sysctl, then we 
may well have to do this one weekend and as you have hinted, it could all 
be a massive waste of time if there's no difference in the results!

cheers, Andy

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