On 04/18/2018 03:45 PM, Dennis Clarke wrote: > On 18/04/18 05:28 PM, Jack Stalnaker wrote: >> I upgraded gcc from 4.8.2 to 7.3.0. I also upgraded binutils to 2.30 >> (from >> the default installed on scientific linux 5). >> >> Unfortunately, the executable I get is now 5 times slower consistently. I >> have changed nothing about the code itself. I have not changed any >> compilation options either. I'm honestly shocked by such a dramatic >> slowdown. Has something changed significantly between these two versions? >> >> I realize I haven't given any information about the code itself (it's >> a mix >> of fortran and c), but the important thing is the significant slowdown >> when >> only the compilation chain has changed. >> >> Can anyone give me any insight as to what might be happening or how to >> address it? >> > > With no code at all to consider ? Not likely. Take a look at your > optimization options and your settings for "march/mtune" etc in case > you had those. Look at the actual online manual for 7.3.0 and check > your options as a LOT has changed and a lot deprecated. Given a 5x slowdown, it's not likely arch/tuning options. But without code there's really nothing we can do -- even reasonable speculation is impossible. jeff
