Re: [PATCH] Skip tsc synchronization checks if CONSTANT_TSC bit is set.

From: Andi Kleen
Date: Wed Oct 22 2008 - 18:46:54 EST

> Not really, there are problems with the pm timer too, the one about
> missing the counter wrap and time dropping in chunks of 4 seconds.
> Tried to explain it over here,

Well then pit. Or are you saying time is always broken on VMware & Linux?

> So TSC is the ideal clocksource from performance and correctness point
> of view for VMware.

But you don't seem to emulate it "ideal"ly otherwise you wouldn't
need all these hacks you're adding?

I think you should either implement a TSC that matches what
real hardware does (including CPUID semantics) or implement
a real vmware PV timer and just say it's PV and not fully virtualized.
But doesn't the vmware paravirt ops have that already anyways?

But I personally think it wouldn't really scale to add detection for
more and more "nearly PV" hypervisors to the standard native kernel.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at