Messages in this thread | | | Date | Wed, 9 Nov 2016 18:17:19 -0200 | From | Marcelo Tosatti <> | Subject | Re: [PATCH] kvm: kvmclock: let KVM_GET_CLOCK return whether the master clock is in use |
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On Wed, Nov 09, 2016 at 06:12:50PM -0200, Marcelo Tosatti wrote: > On Wed, Nov 09, 2016 at 05:48:15PM +0100, Paolo Bonzini wrote: > > Userspace can read the exact value of kvmclock by reading the TSC > > and fetching the timekeeping parameters out of guest memory. This > > however is brittle and not necessary anymore with KVM 4.11. > > Hi Paolo, > > Can you point to commit or explanation why that is not the case anymore? > Thanks
I don't see how thats possible given the:
* TSC * TSC (timer interrupt + TSC deltas) (AKA host TSC clocksource and * CLOCK_MONOTONIC).
Clocks currently drift from each other (therefore are not monotonic).
Have you confirmed CLOCK_MONOTONIC_RAW and TSC are monotonic?
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