Re: False alarm (Re: reshape slowdown?)

[Francesco Potorti`]

>On Athlon MP 2000 MHz:
>
>octave:3> s=rand(3000);
>octave:4> tic; a=s'; toc
>ans = 1.9846
>
>On Athlon XP 1666 MHz -> 0.9 second.

>I know what is the problem now. I do not know how to solve it.
>The problem is that when running in SMP mode the task is bouncing between
>two CPUs flushing the caches. That can be verified booting in UP mode.
>So on my system in UP mode:
>
>octave:1> a=rand(3000);
>octave:2> tic; b=a'; toc
>ans = 0.80099
>
>Which is 3 times faster!

This is awfully slow with respect to what I would (wrongly?) expect.  On
my very old Pentium II 350 MHz, I get:

octave> s=rand(3000);
octave> tic; a=s'; toc
ans = 2.6762
octave> version
ans = 2.1.64

using the latest Debian package.  Why is my box only three times as slow
as an Athlon 2000 on matrix transpose?

-- 
Francesco Potortì (ricercatore)        Voice: +39 050 315 3058 (op.2111)
ISTI - Area della ricerca CNR          Fax:   +39 050 313 8091
via G. Moruzzi 1, I-56124 Pisa         Email: address@hidden
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