Hyperthreading hurts 5.3?

Anthony Atkielski atkielski.anthony at wanadoo.fr
Wed Jan 12 16:43:56 PST 2005

Andrea Venturoli writes:

AV> FWIW I tried numerical computations on a P4 with HT enabled: I expected
AV> using 2 threads might give *at least slightly* better results, but I
AV> could come to the conclusion that with 1, 2 or 4 threads the performance
AV> gain (or loss) was exactly zero.

Where these computations in which all threads were doing pretty much the
same thing?  And was it floating-point?  (Doesn't the processor have
just one FPU, or something like that?)

AV> BTW, an old AMD 2000 XP+ would in any case almost outperform a P4 3GHz,
AV> but that's another story.

An AMD processor will also melt or catch fire if the CPU fan fails,
whereas an Intel processor won't. I found this out the hard way, and so
henceforth I'll be installing Intel processors. The cost savings one
gets from buying AMD isn't enough to pay for a new motherboard or PC.

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

I have no easy way to measure the performance on my system, so I'm
mostly just speculating--but it seems logical.


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