On 19/06/20 20:49, Jim Mattson wrote: > On Fri, May 8, 2020 at 1:36 PM Jim Mattson <jmattson@xxxxxxxxxx> wrote: >> >> I'm still not entirely convinced that the Linux hrtimer can be used to >> accurately emulate the VMX-preemption timer... > > It can't, for several reasons: > > 1) The conversion between wall-clock time and TSC frequency, based on > tsc_khz, isn't precise enough. > 2) The base clock for the hrtimer, CLOCK_MONOTONIC, can be slewed, > whereas the TSC cannot. > 3) The VMX-preemption timer is suspended during MWAIT; the hrtimer is not. > > Is there any reason that VMX-preemption timer emulation shouldn't just > be a second client of the hv_timer, along with lapic timer emulation? I don't think so, you'd just need logic to multiplex it. Paolo
