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
