Fastest timecounter ?

[Sergey Babkin]

>From: David Malone <dwmalone at maths.tcd.ie>

>The TSC is always fastest, but unfortunately under some circumstances
>it can't be trusted (if your CPU has throttle modes to save power
>or on some SMP systems where the two TSCs in each CPU give different
>values).

If I remember correctly, all the SMP CPUs on the same
bus should give the same values (since they are
synchronized and reset from the same signals).
The discrepancy may appear on machines with
multiple bridged front-side buses, essentially the
NUMA machines (such as those with over 4 Intel CPUs).

-SB