...auto-parallelization is extremely stupid, in that it will add a synchronisation overhead to every execution of every inner loop, even if the loop would complete on a single core in much less time than it takes to do the synchronisation. So there is a good chance that enabling it would actually slow down the application.
Note that according to http:// gcc.gnu. org/wiki/ Graphite/ Parallelization and the linked document
http:// gcc.gnu. org/wiki/ AutoparRelated? action= AttachFile& do=get& target= autopar_ performance_ testresults. pdf
...auto- parallelization is extremely stupid, in that it will add a synchronisation overhead to every execution of every inner loop, even if the loop would complete on a single core in much less time than it takes to do the synchronisation. So there is a good chance that enabling it would actually slow down the application.