That benchmark page I referenced shows scaling on a SkylakeX at 1, 26, and 52 cores, on a Haswell at 1, 12, and 24 cores, and on Zen1 at 1, 32, and 64 cores so

That benchmark page I referenced shows scaling on a SkylakeX at 1, 26, and 52 cores, on a Haswell at 1, 12, and 24 cores, and on Zen1 at 1, 32, and 64 cores so you can probably map out a ballpark scaling co-efficent from that. I'm sure there are theoretical and practical limits but it's probably completely dependent on implementation and each system architecture, but that's beyond my pay grade. Maybe start here: https://en.wikipedia.org/wiki/Basic_Linear_Algebra_Subprograms https://en.wikipedia.org/wiki/Basic_Linear_Algebra_Subprogra...