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. Dennis
