Multiple BLISBLAS Threads on Workers

[carstenbauer]

@andrew-saydjari

First, is that also true for BLIS_NUM_THREADS?

I don’t know, but it would certainly be great to figure this out and add it to the docs you mentioned.

@andrew-saydjari

And, if I wanted to take advantage of the hyperthreading, would I want to launch each worker with two julia threads, and set BLIS_NUM_THREADS=1 and OPENBLAS_NUM_THREADS=1?

That largely depends on the application specifics. In general, I tend to avoid using hyperthreads. They can give a speed up for certain workloads but they may also have the opposite effect and also add quite a bit of complexity.

@andrew-saydjari

Currently, I manually set the worker → cpu mapping manually as below. Any obvious ways to adapt that to the case I am proposing where we have two threads per worker?

IIUC, you would benefit from MPI: Improve "manual" pinning (`pinthreads_mpi`) · Issue #61 · carstenbauer/ThreadPinning.jl · GitHub (if generalized beyond MPI). It’s not high on my priority list but will hopefully happen at some point. Feel free to move this forward yourself if you want to.