On Thu, 18 Jul 2019 13:30:09 -0400 Sarah Goslee <sarah.gos...@gmail.com> wrote:
> I'm not even remotely a hardware expert: if the difference is due to > changes in the instruction set, I assume that has potential > consequences for other things, and I just happened to spot it in this > particular case because it's visualization-based? (Yikes.) Yes, this might be bad. I have heard about OpenBLAS (specifically, the matrix product routine) misbehaving on certain AVX-512 capable processors, so much that they had to disable some optimizations in 0.3.6 [*], which you already have installed. Still, would `env OPENBLAS_CORETYPE=Haswell R --vanilla` give a better result? > As it says in my first email (but way at the bottom), I'd already > gotten as far as locating the problem in this line from > grDevices::convertColor() > > xyz <- from$toXYZ(color, from.ref.white) Thanks for confirming this! It felt that I had to make sure, since the behaviour we observe is so confusing. > > (red.xyz <- grDevices::colorspaces$sRGB$toXYZ(red.rgb, > > white.point))[1,] > [1] 0.7733981 0.9280769 0.1383974 > > # [1] 0.4168213 0.2149235 0.0195385 One last check: would red.rgb %*% as.list(environment(grDevices::colorspaces$sRGB$toXYZ))$M still produce different results on your computers? > blas.x86_64 3.8.0-12.fc30 > openblas.x86_64 0.3.6-2.fc30 I do not know enough about Fedora's "alternatives" system, but it does look like R is using OpenBLAS. > A: working > Model name: Intel(R) Xeon(R) CPU E5-1650 v3 @ 3.50GHz > B: not working > Model name: Intel(R) Core(TM) i9-7900X CPU @ 3.30GHz Again, this points in the direction of OpenBLAS not doing AVX-512 math properly. Let's hope that OPENBLAS_CORETYPE=Haswell solves it. -- Best regards, Ivan [*] https://github.com/xianyi/OpenBLAS/issues/1955 https://github.com/xianyi/OpenBLAS/issues/2029 https://github.com/xianyi/OpenBLAS/issues/2168 https://github.com/xianyi/OpenBLAS/issues/2182 ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
