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Re: Extremely poor performance crunching random numbers under PIV-FC5



Hey nice work!  It seems the problem is bracketed into glibc random_r
and rand in the dynamic lib.

Yes. Is it possible to debug glibc in order to find out what is the
source of the slowdown?

On the other hand, I have install single-cpu kernel for FC5.
Beforewards I was working with SMP version because of the
Hyperthreading. Now it runs single cpu kernel and the results are the
same or similar:

# ./dynamic-test-cpu-2
Reservado 0.1 Gb de memoria en 0.000 s.
Escritura sobre 0.1 Gb de memoria en 0.600 s.
10 M de rand() en 45.560 s. (ejemplo.: 1997016613)
10 M de sqrt(i) en 0.210 s. (ejemplo.: 3162)
10 M de log(i) en 9.420 s. (ejemplo.: 16)
10 M de log10(i) en 9.520 s. (ejemplo.: 6)
LINUX: 10 M de random() en 38.900 s. (ejemplo.: 1682960195)
LINUX: 10 M de random_r() en 19.610 s. (ejemplo.: 1997016613)
LINUX: 10 M de lrand48() en 31.240 s. (ejemplo.: 627140866)

Do you think Hyperthreading could be responsible of the slowdown?


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