# BLAS performance testing for Julia 1.8

**URL:** https://discourse.julialang.org/t/blas-performance-testing-for-julia-1-8/69520
**Category:** Performance
**Tags:** blas, multithreading
**Created:** [October 10, 2021, 6:50pm UTC](https://discourse.julialang.org/t/blas-performance-testing-for-julia-1-8/69520 "2021-10-10T18:50:46Z")
**Posts on this page:** 1
**Showing post:** 12

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### Author: ![carstenbauer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/carstenbauer/32/4981_2.png) [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)
#### Post date: [October 13, 2021, 8:04am UTC](https://discourse.julialang.org/t/blas-performance-testing-for-julia-1-8/69520/12 "2021-10-13T08:04:29Z")

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> [@viralbshah](#):
>
> We really need to only use as many threads as the hardware has. Without Hwloc, is there a way to detect physical cores?

A side comment / feature request 😀: We have `JULIA_EXCLUSIVE=1` for compact pinning of Julia threads (i.e. pin 1:N Julia threads to the first 1:N cores). If we had more information about the system (Sockets / NUMA domains), we could also offer a “scattered pinning”, where Julia threads are pinned to cores from both sockets in an alternating fashion. This can have a big influence on performance (MFlops/s), see e.g. [GitHub - JuliaPerf/BandwidthBenchmark.jl: Measuring memory bandwidth using TheBandwidthBenchmark](https://github.com/carstenbauer/BandwidthBenchmark.jl#compact-vs-scattered-pinning) (Also check it out if you just like unicode plots 😃).

But let me stop derailing this thread 🙂

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