On Mon, Mar 16, 2020 at 03:19:55PM +0300, Kirill A. Shutemov wrote: > On Mon, Mar 16, 2020 at 11:18:56AM +0100, Michal Hocko wrote: > > While this might be true, isn't that easily solveable by the existing > > ALTERNATIVE and cpu features framework. Can we have a feature bit to > > tell that movnti is worthwile for large data copy routines. Probably > > something for x86 maintainers. > > It still need somody to test which approach is better for the CPU. > See X86_FEATURE_REP_GOOD. How about inverting the sense of the bit? Set it on Broadwell-and- earlier CPUs, where it definitely improves performance by a huge amount, and new microarches can set it if it still outperforms rep mov?
