Messages in this thread | | | Date | Sat, 6 Oct 2018 17:27:33 -0300 | From | Marcelo Tosatti <> | Subject | Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support |
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On Thu, Oct 04, 2018 at 03:15:32PM -0700, Andy Lutomirski wrote: > For better or for worse, I'm trying to understand this code. So far, > I've come up with this patch: > > https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/vdso-tglx&id=14fd71e12b1c4492a06f368f75041f263e6862bf > > Is it correct, or am I missing some subtlety?
The master clock, when initialized, has a pair
masterclockvalues=(TSC value, time-of-day data).
When updating the guest clock, we only update relative to (TSC value) that was read on masterclock initialization.
See the following comment on x86.c:
/* * * Assuming a stable TSC across physical CPUS, and a stable TSC * across virtual CPUs, the following condition is possible. * Each numbered line represents an event visible to both * CPUs at the next numbered event. ...
When updating the "masterclockvalues" pair, all vcpus are stopped.
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