On 19:12 Mon 10 Feb , Jeff Squyres (jsquyres) wrote: > 1. Should we cache generated prime numbers? (if so, it'll have to be done in > a thread-safe way)
The code I've submitted in the other thread is much faster than the original code (e.g. 100x faster for 10000 nodes, the ratio increases with the number of nodes). Given that MPI_Dims_create is a function typically called once at application startup, I don't think caching was of great benefit. > 2. Should we just generate prime numbers and hard-code them into a table that > is compiled into the code? We would only need primes up to the sqrt of > 2billion (i.e., signed int), right? I don't know how many that is -- if it's > small enough, perhaps this is the easiest solution. Could be done, but it's not much faster than the current code. Plus it's just calling for bugs (MPICH does this and their (initial) code easily segfaulted). Best -Andreas -- ========================================================== Andreas Schäfer HPC and Grid Computing Chair of Computer Science 3 Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany +49 9131 85-27910 PGP/GPG key via keyserver http://www.libgeodecomp.org ========================================================== (\___/) (+'.'+) (")_(") This is Bunny. Copy and paste Bunny into your signature to help him gain world domination!
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