Hi, Timothee Mathieu <[email protected]> writes:
> We finally managed to prove that the problem was with avx-512 by using > qemu we can enable/disable avx-512 and do the computation with exactly > the same guix pack and recover that this gives different results. The > qemu avx-512 results match bitwise the results from laptop on Ubuntu > that have avx-512 and conversely that the qemu without avx-512 have > the same results as the Arch laptop that also does not have AVX-512. Are you saying that the same binaries in the same pack use AVX-512 when available and don’t use it otherwise? This is the “ideal” load-time adjustment¹ but then you could run into the kind of numerical issue that you experience. It’s a problem that I would discuss with the authors of the library, perhaps starting with mujoco itself. Interesting case anyway! Ludo’. ¹ Discussed in <https://hpc.guix.info/blog/2018/01/pre-built-binaries-vs-performance/> and used by libraries like glibc, OpenBLAS, and more.
