Precision of time_since_epoch

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#include <chrono>
uint64_t timestamp = std::chrono::system_clock::now().time_since_epoch().count();

'timestamp' is in ns, not in us(μs or microsecond).

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1 s = 1000 ms
1 ms = 1000 μs
1 μs = 1000 ns
1 ns = 1000 ps
 
2 GHz = 2 x 10^9 Hz, its 1 circle has 0.5 ns long.