------- Comment #11 from changpeng dot fang at amd dot com 2010-06-01 17:40 ------- (In reply to comment #10) > Created an attachment (id=20783) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20783&action=view) [edit] > experimental patch to have separate values for min_insn_to_prefetch_ration > > Changpeng, > > thank you for the feedback. > Can you confirm that the regression was introduced by a prefetch with an > unknown step or is there still a bug in the calculation of the "normal" > prefetches (e.g. by applying the first patch that disables non-constant steps) > > Anyway, here is a patch that increases min_insn_to_prefetch_ratio for > non-constant steps. Does that make a difference for tonto? Do you prefer other > intial values? > Thanks > > Christian > Hi, Christian:
For constant step prefetching only, tonto regressed by ~7%, and for const + invariant step prefetching combined, it regressed by ~16%. I should have mentioned earlier that non-constant step prefetching has improved 459.GemsFDTD by 4~5% on amd-linux64 systems, and tonto regression by non-constant step prefetching should be able to be fixed by re-compute the prefetch count by considering the unroll_factor. However, I have found the non-temporal store problem which can cause 416.gamess degradation by ~50%. I am not sure whether it is caused by non-constant step prefetching or not. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44297
