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 15:00:46 -0700 |
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[dropped LKML of the cc list]
Hi Andi,
On Wed, 2008-10-22 at 12:58 -0700, Andi Kleen wrote: > > We also force set the CONSTANT_TSC capability bit if we are running on > > VMware, since the VMware hypervisor exports a constant TSC to the guest. > > NAK. > > The whole point of this is to eliminate the need for vmware detection, > which is something the kernel shouldn't need to know about. > Instead VMware should supply that bit by itself and then Linux could > do the right thing. The only change you would need to do is to always > check it for all CPU vendors, not just AMD.
Yeah, i can add that code which checks for that bit, for all cpu vendors. And yes we can supply that bit with our future products.
> Adding it with vmware detection code is not useful.
The VMware detection code is something that's needed anyways for other purposes(getting tsc_freq right now). So the code which force sets this TSC_CONSTANT bit is trivial. Apart from that, as i said yesterday, this should be viewed as a special case for VMware products which don't already set this bit. Changing the behavior for already existing products is not feasible.
Thanks, Alok
> > -Andi
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