CPUClockCounter is not NTP adjusted (CLOCK_MONOTONIC_RAW) so should be
better for measurements. However, it is implemented with syscall while
CLOCK_MONOTONIC is implemented via vDSO. The latency increase becomes
significant when language layers make corresponding clock measurements.
Reverting to CLOCK_MONOTONIC will reduce latency and allow small
duration events to be measured at the cost of incorporating NTP
frequency skew errors. NTP may adjust frequency by 500ppm so limits us
to ~3 decimals in elapsed time.
Change-Id: I920b9f707f47109d80d6c256c475638c03fb8d76
Sean Keely
4b22d24346