Hyperthreading hurts 5.3?

Andrea Venturoli ml at netfence.it
Wed Jan 12 12:53:01 PST 2005

Anthony Atkielski wrote:

>>From what you say and from what I've read today, it sounds like
> hyperthreading comes close to providing two separate processors for
> heterogenous system loads (where each hyperthread is using slightly
> different processor resources at any given instant), but it may not buy
> much of anything for massively parallel compute-bound work,

FWIW I tried numerical computations on a P4 with HT enabled: I expected 
using 2 threads might give *at least slightly* better results, but I 
could come to the conclusion that with 1, 2 or 4 threads the performance 
gain (or loss) was exactly zero.
(BTW, an old AMD 2000 XP+ would in any case almost outperform a P4 3GHz, 
but that's another story).

Obviously your use (as a server) is very different, and probably the one 
test I have done can't expect to achieve 100% coverage even in this 
field... but, anyway, just my 2 cents...


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