The timestamp is the 32 Least Significant Bits (LSB) part of the 64-bit clock. Whenever the 32-bit portion of the clock rolls over, a _NTO_TRACE_CONTROLTIME control event is issued. Although adjacent events will never have the same exact timestamp, there may be some timestamp duplication due to the clock's rolling over.

The rollover control event includes the 32 Most Significant Bits (MSB), so you can reassemble the full clock time, if required. The timestamp includes only the LSB in order to reduce the amount of data being generated. (A 1-GHz clock rolls over every 4.29 seconds—an eternity compared to the number of events generated.)

Note: Although the majority of events are stored chronologically, you shouldn't write code that depends on events being retrieved chronologically. Some multiple buffer slot events (combine events) may be interlaced with others with leading timestamps. In the case of buffer overruns, the timestamps will definitely be scrambled, with entire blocks of events out of chronological order. Spurious gaps, while theoretically possible, are very unlikely.