[Numpy-discussion] Different results from repeated calculation
fperez.net at gmail.com
Sat Jan 27 18:52:35 EST 2007
On 1/27/07, Robert Kern <robert.kern at gmail.com> wrote:
> Fernando Perez wrote:
> > That's it. One comment char removed, and something that's done
> > /after/ the tests are actually executed.
> > That kind of 'I add a printf() call and the bug disappears' is
> > unpleasantly reminiscent of lurking pointer errors in C code...
> Heh. Fantastic. It might be worthwhile porting this code to C to see what
> happens. If we can definitively point the finger at the kernel, that would be
> great (less work for me!).
It's definitely looking like something SMP related: on my laptop, with
everything other than the hardware being identical (Linux distro,
kernel, numpy build, etc), I can't make it fail no matter how I muck
with it. I always get '0 differences'.
The desktop is a dual-core AMD Athlon as indicated before, the laptop
is an oldie Pentium III. They both run the same SMP-aware Ubuntu i686
kernel, since Ubuntu now ships a unified kernel, though obviously on
the laptop the SMP code isn't active.
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