Ok. Miscommunication. Different kernels. I was actually asking "which Linux kernel functions are going to benefit from auto-vectorization. There are not a lot of Linux kernel functions that take arguments that are two arrays of floating point values. Lots of string stuff that typically doesn't vectorize well (except in freakish cases), perhaps. But very very few functions that take arrays of floats as arguments. Yes, graphics libraries if you want to count those as kernel functions; but those primarily concern themselves with passing arrays of floats to co-processors, to be vectorized by a GPU (different problem).
As an interesting point of reference, the last time I did Windows kernel development (which was admittedly not recently), code running in ring 0 was not allowed to access SIMD registers because they weren't saved and loaded during kernel-code context switches. Not sure if that's the case, but it probably is. Context switches are a LOT faster if you don't have to save and load SIMD registers.
As an interesting point of reference, the last time I did Windows kernel development (which was admittedly not recently), code running in ring 0 was not allowed to access SIMD registers because they weren't saved and loaded during kernel-code context switches. Not sure if that's the case, but it probably is. Context switches are a LOT faster if you don't have to save and load SIMD registers.