Friday, October 14, 2011

working with openmp and gcc vectorization output

When working with openmp for parallelisation you can set the number of threads in a bash shell (cygwin) by


this can be good to do if you do not want to use all "cores" detected automatically on a cpu with hyperthreading.

To see which loops have been automatically vectorized by gcc you have to add the compiler switch


Other verbose levels can also be used but for me level 5 seems to give the most relevant information.