Re: How to get GCC on par with ICC?

[Zan Lynx <zlynx at acm dot org>]

On 06/06/2018 10:22 AM, Dmitry Mikushin wrote:
> The opinion you've mentioned is common in scientific community. However, in
> more detail it often surfaces that the used set of GCC compiler options
> simply does not correspond to that "fast" version of Intel. For instance,
> when you do "-O3" for Intel it actually corresponds to (at least) "-O3
> -ffast-math -march=native" of GCC. Omitting "-ffast-math" obviously
> introduces significant performance gap.
> 

Please note that if your compute cluster uses different models of CPU,
be extremely careful with -march=native.

I've been bitten by it in VMs, several times. Unless you always run on
the same system that did the build, you are running a risk of illegal
instructions.

-- 
                Knowledge is Power -- Power Corrupts
                        Study Hard -- Be Evil