2012年10月17日 · The <chrono> implementation in libc++ for Darwin provides nanosecond resolution, but it seems the implementation in VS2012 only goes to tenths of milliseconds. The above code will still give times in terms of nanoseconds, but timings less than 100 microseconds will end up being zero nanoseconds.

2022年4月30日 · You are never going to get nanosecond accuracy. Think about what you are asking: on a 1 GHz CPU 1 nanosecond is a clock cycle. No matter what you attempt to call, you will never get that kind of accuracy, you are better off sticking to microseconds. A similar question with many examples is here: C++ Cross-Platform High-Resolution Timer.

2018年8月29日 · Even you have previously managed to sync the hardware clock with a "real" time source to nanosecond accuracy, the overheads and variability in the making the above calls to acquire the epoch nanosecond time would swamp the hardware clock's nanosecond accuracy. Things like memory cache variability, how busy the main memory bus is, etc.

2013年12月19日 · Be aware that there is no clock available in nanosecond resolution (real time). The internal nanosecond representation facility of java.time.Instant is mainly due to the requirement to map database timestamps given in nanosecond precision (but normally not accurate to nanoseconds!).

2014年12月28日 · How can I print the current time using the std::chrono library? I would like the format to be: hour:minute:second:millisecond:microsecond:nanosecond.

2008年11月9日 · All this clock does is count CPU cycles and store it in an unsigned 64-bit integer. You may need to tweak the assembly language syntax for your compiler. Or your compiler may offer an intrinsic you can use instead (e.g. now() {return __rdtsc();}). To build a clock you have to give it the representation (storage type).

2020年2月28日 · Java uses Clock class to get current instant. Clock.systemUTC() return best available system clock instance which could return more precise timestamp. That said, Java 8 on Windows uses System.currentTimeMillis() as a source so it returns millisecond-precise time. But that's not guaranteed and other implementations can provide more precise time.

2012年12月19日 · @resting: CLOCK_MONOTONIC represents time since some unspecified time in the past (e.g. on Linux zero is set to some time before the boot time of the system), and is monotonic, i.e. does not change e.g. if the system clock is changed. CLOCK_REALTIME represents time since the epoch. –

To summarise information presented so far, these are the two functions required for typical applications. #include <time.h> // call this function to start a nanosecond-resolution timer struct timespec timer_start(){ struct timespec start_time; clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start_time); return start_time; } // call this …

2009年12月21日 · @Jcyrss, time_ns does not provide nanosecond resolution, it just returns the time in nanoseconds. This may or may not improve the resolution. Measured clock resolutions for Linux and Windows are documented in PEP 564. For Windows, the measured resolution of time_ns was 318 us. –