[Numpy-discussion] Openmp support (was numpy's future (1.1 and beyond): which direction(s) ?)
James Philbin
philbinj at gmail.com
Sat Mar 22 14:54:43 EDT 2008
> However, profiling revealed that hardly anything was gained because of
> 1) non-alignment of the vectors.... this _could_ be handled by
> shuffled loading of the values though
> 2) the fact that my application used relatively large vectors that
> wouldn't fit into the CPU cache, hence the memory transfer slowed down
> the CPU.
I've had generally positive results from vectorizing code in the past,
admittedly on architectures with fast memory buses (Xeon 5100s). Naive
implementations of most simple vector operations (dot,+,-,etc) were
sped up by around ~20%. I also haven't found aligned accesses to make
much difference (~2-3%), but this might be dependent on the
architecture.
James
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