Dear Joachim,
On 08/09/2017 19:12, Joachim Hein wrote:
Hi
For building git, it seems I require Perl. I think git would sit nicely in
GCCcore (instead of foss/intel). Is there a reason why the new Perl 5.26.0
sits in intel/2017b or foss/2017b instead of GCCcore 6.4.0?
I assume if I build a Perl in GCCcore for git I get nice conflicts with
anything loaded simulaneously taking it out of foss/intel at runtime?
Up until now, we've usually been installing Perl at the foss/intel level
(unless we needed it as a build dep for something built with GCCcore).
This has sort of grown historically (we've always been doing it like
that at HPC-UGent), the main motivation being is that we tend to compile
all end-user applications with Intel compilers (I also included the
'foss' equivalent for Perl 5.26.0 since it was dead-easy to do so).
I have to admit I never really benchmarked whether it's necessary to
build Perl with Intel compilers for better performance, I just assumed
it would be beneficial.
Yesterday I did a quick benchmarking session using the Perl-Formance
package [1], and I ran into some surprising results: the Perl that was
built on top of GCCcore was significantly faster than the same
installation done with intel/2017b...
For several of the tests included in Perl-Formance, I saw 10-15%
*longer* runtimes with Perl/5.26.0-intel-2017b compared to using
Perl/5.26.0-GCCcore-6.4.0;
for one test, there even was a ~40% difference, but only on one of two
systems I tested on (Sandy Bridge, not observed on Haswell).
So, I shouldn't have made the assumption that compiling with Intel
compilers yields better performance, I should have checked.
Disclaimer: these results may be specific to the benchmark tests used,
and the versions of Perl and the compilers, the conclusion may change
over time...
Long story short:
https://github.com/easybuilders/easybuild-easyconfigs/pull/5126
To answer your questions w.r.t. conflicts: since Perl is only a build
dependency for git, you shouldn't run into conflicts on Perl when
combining git with something else that was built including Perl built
with intel toolchain as a dependency.
regards,
Kenneth
[1]
https://metacpan.org/pod/distribution/Benchmark-Perl-Formance/bin/benchmark-perlformance
