SPEChpc™ 2021 Known Problems

$Id$ Latest: www.spec.org/hpg/hpc2021/Docs/



Known limitations

Open Problem Reports

Closed Problem Reports


This document describes known problems in SPEChpc 2021.

Do you have a problem with SPEChpc?
Try these, in this order:

  1. Update your copy with runhpc --update.
  2. Check the latest version of Frequently Asked Questions.
  3. Check the latest version of Known Problems.
  4. Check the src.alt list.    [What is a src.alt?]
  5. Contact SPEC.

SPEChpc 2021 was tested on a variety of systems prior to release, including x86, Power, and ARM Linux systems. Nevertheless, as with any software product, problems may be found too late in the testing process to be fixed in the release, or may be discovered after release.

If you discover problems that are not listed here or in the FAQ, please report them to SPEC.

About the format of this document:

Notice to maintainers: When updating this document, please do not ever re-use problem numbers.

Known Limitations

The current list of known limitatons:

BenchmarkDescriptionWork around
LBMLBM may fail to validate when using larger ranks counts, usually 2-4x that of the upper tested limit for each suite.Use fewer ranks or use a suite intended for larger rank counts.
LBMv1.1 added host parallelization for the initialization loop in OpenMP with Target Offload and OpenACC. OpenACC uses the "self" clause which is not supported by all compilers. Add the define flag "-DSPEC_OPENACC_NO_SELF" to fallback to using an OpenMP "parallel loop" for OpenACC.
miniSweepminiSweep may not validate with odd ranks counts (except 1 or 3).Use even rank counts
SOMASOMA uses array reductions for OpenMP and OpenACC when the compiler claims support for the standard where array reductions were added. OpenMP=>201511, OpenACC=>201811. However some compilers do not actually include support for array reductions.Add the define flag -DSPEC_NO_VAR_ARRAY_REDUCE to use an alternate source version that does not use array reductions. Note that since the alternate version is run serially on the host, it's expected to be less performant.

Open Problem Reports

Please see the latest on-line version of this document for information on open problems and suggested workarounds.

BenchmarkDescriptionWork around
No known issues.

Closed Problem Reports

miniSweepminiSweep OpenMP may intermittently hang for certain compilers. Fixed in v1.1. Removed the "depend" clause which was found to be the source of the hang.

SPEChpc™ 2022 Known Problems: Copyright © 2021 Standard Performance Evaluation Corporation (SPEC)