Telcon: 2026 02 11

Wednesday February 11th, 9am PT (UTC -8:00)

(Invite Link: https://zoom.us/j/93354081914?pwd=kkovIeyqQPkb9KgQUKKgOnV3kWafS0.1)

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Attendees

• Peter Scheibel (host)
• Davide
• pgoetz
• Diego Menéndez
• Christopher Haley
• Mark Yoder

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Agenda

This is for Q&A: there are currently no pre-planned topics

• Davide: when I was building openmpi in Spack, the default build options were different than if you built it outside of spack. The defaults that were chosen in spack resulted in something about 10x slower
  • someone in slack mentioned to use openmpi~vt fabrics=ucx ^ucx@1.19 +rc simd=auto +ud +verbs +mlx5_dv
  • I had thought I'd installed ucx with these params, so I did openmpi~vt fabrics=ucx ^/hash and it failed
    • The error message just said "openmpi@5 cannot be satisfied"
  • Testing ^cmd-line-spec works, want to know the difference
  • Can this be done easily w/ spack diff
  • Comparing manually, the cmd-line-spec requested +thread_multiple
  • Manually trying ucx~thread_multiple appears to cause an error with openmpi@5
• pgoetz: context: I want to set up spack, users in my env have small homedirs
  • Grabbed 1.1.1 tarball, untarred it into NFS mounted FS
  • on ubuntu 24.04
  • Default install tree is $spack/opt/spack
  • 2 compilers installed: gcc 13 and clang 18
  • First tried to build gcc 15.2.0, spack install gcc@15.2.0, crashed while compiling ncurses
    • It chose clang for it
    • someone suggested spack install gcc@15... %gcc@13.3.0
    • Uninstalled clang from my base system, only have gcc, failed again
  • chatgpt suggested using compilers.yaml
  • Starting up again, unpack tarball, spack compiler find, spack spec gcc@15.2.0,
    • bootstrapping clingo is slow (install is >40 minutes)
    • Maybe we should add binary cache https://cache.spack.io/tag/develop/ spack mirror add develop https://binaries.spack.io/develop spack buildcache keys --install --trust
• Diego: using projection all: '{architecture.platform}-{architecture.target}/{name}-{version}_{compiler.name}-{compiler.version}'
  • This prints none-none for items that do not use compilers
  • Peter: maybe https://spack.readthedocs.io/en/latest/environments.html#view-projections (that's for envs and is not necessarily about projection of the install tree)
  • Some projection entries would be like `%c: {architecture.platform}-{architecture.target}/{name}-{version}/{%c.name}