> On Aug 29, 2022, at 22:54, Jonathan Gray <j...@openbsd.org> wrote: > > On Mon, Aug 29, 2022 at 12:02:42PM -0500, Scott Cheloha wrote: >> If hv_delay() never causes a vm exit, but tsc_delay() *might* cause a >> vm exit, and both have microsecond or better resolution, then >> hv_delay() is the preferable delay(9) implementation where it is >> available because vm exits have ambiguous overhead. > > with hv_delay() currently doing rdmsr I wouldn't say never > >> >> If that seems sensible to you, I'll commit this switch. > > There is a msr to allow cpuid to report invariant tsc (0x40000118). > Used by linux but not documented in the hyper-v tlfs. > > Without that, tsc delay is never used on hyper-v. So leave it > as is until someone running hyper-v/azure would like it changed?
Works for me.
