Bug 784245

Summary:	dev-lang/julia: enable polly and polly-openmp support for automatic parallelization
Product:	Gentoo Linux	Reporter:	Paul Preney <paul>
Component:	Current packages	Assignee:	Gentoo Science Related Packages <sci>
Status:	CONFIRMED ---
Severity:	normal	CC:	ionen, jeffrey, patrick, paul, tamiko
Priority:	Normal
Version:	unspecified
Hardware:	AMD64
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---

Description Paul Preney 2021-04-19 20:42:26 UTC

dev-lang/julia-1.6.0 fails to work with OMP_NUM_THREADS (nothing happens at all) built with USE=system-llvm and without.

dev-lang/julia-bin-1.6.0 does work with OMP_NUM_THREADS properly.

It doesn't matter what eselect blas and/or eselect lapack is set to --the results are the same.

Reproducible: Always

Steps to Reproduce:
1. Install =dev-lang/julia-1.6.0.
2. Execute Julia code such as:
  n = 3_000;
  A = rand(n,n);
  B = A[:,:];
  C=similar(A);
  @time mul!(C,A,B)
Timings differ (correctly) if OMP_NUM_THREADS are set to different values before running julia1.6 in dev-lang/julia-bin. dev-lang/julia does not appear to honour OMP_NUM_THREADS.
Actual Results:  
dev-lang/julia always takes the same amount of time to run regardless of what OMP_NUM_THREADS is set to.

Expected Results:  
When OMP_NUM_THREADS is set the time required should decrease (assuming one has enough physical cores).

Comment 1 Matthias Maier gentoo-dev

2022-01-03 22:16:13 UTC

Let's see whether

  USE_POLLY:=1
  USE_POLLY_OPENMP:=1

enables the openmp support in julia that you are describing.