Messages in this thread | | | Subject | Re: [PATCH] Skip tsc synchronization checks if CONSTANT_TSC bit is set. | From | Alok Kataria <> | Date | Wed, 22 Oct 2008 12:30:40 -0700 |
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On Wed, 2008-10-22 at 12:26 -0700, Ingo Molnar wrote: > * Alok Kataria <akataria@vmware.com> wrote: > > > Skip tsc synchronization checks if CONSTANT_TSC bit is set. > > > > From: Alok N Kataria <akataria@vmware.com> > > > > TSC synchronization checks between CPU's bail out even if we see a > > distortion of a single cycle. This makes the TSC mostly unsuable in a > > virtualized environment. > > > > The CONSTANT_TSC bit tells us if the hardware exports a constant TSC, > > we can use this bit to trust the hardware and skip the TSC sync checks > > at bootup. > > the sync check is there to check the _offset_ between CPUs. CONSTANT_TSC > is not a guarantee that the TSC will be coherent across all CPUs. > > so this patch is fundamentally wrong.
Then does adding a new flag to skip this check be acceptable ? Something like the patch that i had sent yesterday ?
Thanks, Alok
> > Ingo
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