On 21/08/20 11:28, Thomas Gleixner wrote: > We all know that MSRs are slow, but as a general rule I have to make it > entirely clear that the kernel has precedence over KVM. I totally agree. I just don't think that it matters _in this case_, because the kernel hardly has any reason to use TSC_AUX while in ring0. Paolo > If the kernel wants to use an MSR for it's own purposes then KVM has to > deal with that and not the other way round. Preventing the kernel from > using a facility freely is not an option ever. > > The insanities of KVM performance optimizations have bitten us more than > once. > > For this particular case at hand I don't care much and we should just > rip the whole RDPID thing out unconditionally. We still have zero > numbers about the performance difference vs. LSL.
