On Wed, Mar 14, 2018 at 12:55:20PM +0000, Jason Vas Dias wrote: > > If you want to correlate to CLOCK_MONOTONIC_RAW you have to read > > CLOCK_MONOTONIC_RAW and not some random other clock value. > > > > Exactly ! Hence the need for the patch so that users can get > CLOCK_MONOTONIC_RAW values with low latency and correlate them > with PERF CPU_CLOCK values.
No, you _CANNOT_ correlate CLOCK_MONOTONIC_RAW with CPU_CLOCK, that is _BROKEN_. Yes it 'works', but that's mostly a happy accident. There is no guarantee that CLOCK_MONOTONIC_RAW runs off the TSC, and even if both CPU_CLOCK and CLOCK_MONOTONIC_RAW use the TSC, they need not use the same rate (and they didn't for a long time). Do not mix clocks.
