[Users] intel compiler flags?

[Roland Haas]

Hello all,

uhh, let me actually read the question. Frank seems to have pointed you
to what I assume (have not checked yet) to be the proper documentation
that shows what can go wrong. Now for how I worked around the issues myself:

For the symmetric operators branch I use -fp-model precise to the intel
compiler eg on zwicky I use the default zwicky machine defintion file in
simfactory then add "-fp-model precise" to all CFLAGS/CXXFLAGS/F90FLAGS
so that they read:

C_OPTIMISE_FLAGS   = -O2 -xHost -fp-model precise
CXX_OPTIMISE_FLAGS = -O2 -xHost -fp-model precise
F77_OPTIMISE_FLAGS = -O2 -xHost -fp-model precise
F90_OPTIMISE_FLAGS = -O2 -xHost -fp-model precise

for the gnu compiler on bluewaters I had to also disable some
optimizations (I don't know why):

C_OPTIMISE_FLAGS = -O3 -fno-expensive-optimizations -fno-ipa-cp-clone

@Jonah: if you have access to the SXS wiki (say due to Spectre work),
you can find this information on
https://www.black-holes.org/wiki/center_of_mass_conserving_setup
somewhere under the first big table.

Yours,
Roland


On 2015-11-10 22:47, Erik Schnetter wrote:
> Roland, I think you have been using such flags. Which flags exactly did you
> use?
> 
> -erik
> 
> On Tue, Nov 10, 2015 at 1:45 PM, Frank Loeffler <knarf at cct.lsu.edu> wrote:
> 
>> On Tue, Nov 10, 2015 at 01:38:08PM -0500, Jonah Miller wrote:
>>> I am working on developing a modified stencil for the Einstein Toolkit
>>> and I am discovering that regression tests pass when I use the GNU
>>> compilers but fail when I use the Intel compilers, even with gentle
>>> optimization settings such as -O1. I suspect over-zealous optimization.
>>> Has anyone encountered this sort of problem before? And if so, does
>>> anybody know a good combination of flags that makes the intel compiler
>>> more cautious, without sacrificing too much speed? (For example,
>>> disabling fast math, which seems to be set to active by default.)
>>
>> The default for the Intel compiler is non-exact math. Try some of the
>> options mentioned here:
>>
>>
>> https://software.intel.com/en-us/articles/consistency-of-floating-point-results-using-the-intel-compiler
>>
>> How much that influences effective speed likely depends a lot on your
>> code.
>>
>> Frank
>>
>>
>> _______________________________________________
>> Users mailing list
>> Users at einsteintoolkit.org
>> http://lists.einsteintoolkit.org/mailman/listinfo/users
>>
>>
> 
> 
> 
> 
> _______________________________________________
> Users mailing list
> Users at einsteintoolkit.org
> http://lists.einsteintoolkit.org/mailman/listinfo/users
>