[Valgrind-developers] Problem with rdtsc calibration

[Jeremy F. <je...@di...>]

I've noticed that on my laptop the rdtsc calibration often fails with
"impossible MHz".  I think this is because the TSC only advances when
there's something actually happening, as part of the power management.

I've attached a patch (against HEAD) to make it spin rather than sleep
for 20ms as part of the calibration.  This makes the MHz estimate
accurate and solves the panics, but it does imply that the TSC is not a
reliable timebase for other time measurements, which is a larger problem
to solve.

    J