On Wed, Jan 04, 2017 at 05:10:38PM +0800, Paul Goyette wrote: > > The system realtime clock is guaranteed to be monotonically > increasing at all times. As such, all calls to these functions > are guaranteed to return a system time greater than or equal to > the system time returned in any previous calls. > > > The guarantee to return a result "greater than or equal to" the previous > result is a property of a "monotonically non-decreasing" function. A > "monotonically increasing" function would guarantee a results that is > strictly greater than any previous results.
It is strictly non-decreasing, but the expectation is that the result will actually change over time. On a short enough observation interval, it might be constant though. Time counters are a step function and e.g. the Intel RTC has a frequency of ~32kHz, so even on slower CPUs it is easy to observe the constant phases. Joerg