Messages in this thread | | | Date | Thu, 12 Jun 2003 22:59:31 +0200 | From | "J.A. Magallon" <> | Subject | Re: SMP question |
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On 06.12, Scott Robert Ladd wrote: > J.A. Magallon wrote: > > In short, for FP intensive tasks, hyperthreading is a big lie... > > You can't run 2 computations in parallel. > > Yes and no; the benefit of HT depends on the application in question. > I've seen everything from a 5% LOSS in performance to a 30% INCREASE in > performance, for intensive floating-point code. This is with programs > parallelized with OpenMP and Intel's C and Fortran compilers. I'm still > analyzing the exact nature of the benefits, but they *do* exist. > > While I much prefer multiple physical CPUs to "virtual" CPUs, HT *does* > provide performance improvements for certain applications. To call HT a > "big lie" is both provacative and inaccurate. >
I told that because non-techical people just think they are buying _two_ processors, but they really pay too much for 1.25 processors, and that if you fine-tune your code...
-- J.A. Magallon <jamagallon@able.es> \ Software is like sex: werewolf.able.es \ It's better when it's free Mandrake Linux release 9.2 (Cooker) for i586 Linux 2.4.21-rc8-jam1 (gcc 3.3 (Mandrake Linux 9.2 3.3-1mdk)) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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