Conference call notes 20180314

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Notes on the 97th EasyBuild conference call, Wednesday March 14th 2018 (5pm - 6pm CET)

Attendees

Alphabetical list of attendees (5):

• Victor Holanda (CSCS)
• Kenneth Hoste (HPC-UGent)
• Adam Huffman (Big Data Institute, University of Oxford)
• Bart Oldeman (ComputeCanada)
• Davide Vanzo (Vanderbilt University, US)

Agenda

• added check to ensure one single dependency "variant" for easyconfigs using a '2018a' toolchain
  • cfr. https://github.com/easybuilders/easybuild-easyconfigs/pull/5970
• discussion w.r.t. including -ftree-vectorize to default list of compiler options for GCC-based toolchains
  • cfr. https://github.com/easybuilders/easybuild-framework/pull/2388
• Q&A

Enable -ftree-vectorize by default?

• see https://github.com/easybuilders/easybuild-framework/pull/2388
• no vectorization by default when using GCC...
  • lost performance on systems like Skylake
• some concerns w.r.t. FP accuracy
  • OK with default options
• just adding -ftree-vectorize is not enough to get most out of it
  • we could also consider adding -fno-math-errno (does not affect accuracy)
• has been used at ComputeCanada for a couple of weeks, no issues found
• tested at CSCS with GROMACS, regtest still passes
• KH will test with CP2K and foss/2018a
• Victor: what about Clang/PGI?
• seems OK to merge to include in EasyBuild v3.6.0...

Added check in easyconfigs test suite to enforce single dependency variant per toolchain generation

• see https://github.com/easybuilders/easybuild-easyconfigs/pull/5970
• example of detected 'violation': https://github.com/easybuilders/easybuild-easyconfigs/pull/5955#issuecomment-372693309
• Victor: could be useful in eb too?
  • eb --check-conflicts does some of this already (but ignores build deps)
  • implementation in easyconfig test suite could be hoisted into framework to enhance --check-conflicts

Other

• Victor
  • ETA for next release (which includes -ftree-vectorize)?
    • v3.6.0 is planned for mid April'18, may be pushed a little bit earlier if there enough demand...
  • change bi-weekly schedule to avoid clash with GROMACS conf call?
    • will stick to planned dates in April (11th + 25th) for now
    • can consider skipping a week starting May to shift schedule with 1 week
  • --job-max-jobs support for EB v3.6.0?
    • https://github.com/easybuilders/easybuild-framework/pull/2378
  • ways to contribute?
    • review PRs you care about
    • help with reviewing easyconfigs PRs, see http://easybuild.readthedocs.io/en/latest/Contributing.html#review-process-for-contributions
  • filter OS deps via hooks?
    • validating OS deps is done while parsing easyconfig file
    • no hook yet to intervene, could add post-parse hook for that purpose?
  • how to handle EasyBuild configuration & easyconfigs for different platforms (x86, ARM, Cray, ...)?
    • good question for mailing list, could collect info for best practices document on this?
• Bart
  • depends_on support for EB v3.6?
    • https://github.com/easybuilders/easybuild-framework/pull/2391
• easyblock for OpenMPI?
  • --with-verbs vs --without-verbs based on available libraries
    • may need to be careful, don't want to build without IB support by accident...
  • SLURM integration: PMI2 vs PMIx (required for srun)
    • for PMIx, both SLURM & OpenMPI need to be built against sam hwloc
      • only matters with really big jobs (10k+)