Dec 22, 2011 · There are a number of more accurate timers in POSIX. gettimeofday() - officially obsolescent, but very widely available; microsecond resolution. clock_gettime() - the replacement for gettimeofday() (but not necessarily so widely available; on an old version of Solaris, requires -lposix4 to link), with nanosecond resolution.

Linux and POSIX: Even better than timespec_get() in C is the Linux and POSIX function clock_gettime() function, which also works fine in C++ on Linux or POSIX systems. clock_gettime() does allow you to choose the desired clock.

Aug 2, 2016 · @undefined: Not just Linux, it's actually the C standard that says "The clock function determines the processor time used.". I suppose on Windows you can simply say that the implementation's best approximation to processor time used is wall-clock time used. –

Jan 8, 2014 · The function clock is the only way to get sub-second precision, but precision may be as low as one second (it is defined by the macro CLOCKS_PER_SEC). Also, it does not measure real time at all, but processor time. The function time measures real time, but (usually) only to the nearest second.

Jan 11, 2018 · On POSIX clocks are normally implemented using clock_gettime and the resolution can be as high as 1ns as reported by clock_getres. However, you probably want to take into account the overhead of calling the now() function (including the overhead of the underlying API) which can be much higher than the reported resolution.

@starflyer The precision of the clock is partly limited by the amount of time it takes to poll the clock. This is because, if I call the clock and it takes 1 µs to return, then the time the clock reports will be "off" by 1 µs from the perspective of the caller. This means that a highly accurate clock must also be low-latency.

May 18, 2022 · I know that 10 years ago, typical clock precision equaled a system-tick, which was in the range of 10-30ms. Over the past years, precision was increased in multiple steps. Nowadays, there are ways to measure time intervals in nanoseconds. However, usual frameworks still return time with a precision of only around 15ms.

Oct 9, 2016 · The C standard library was designed to be implementable on a wide range of hardware, including processors that don't have an internal timer and rely on an external peripheral to tell the time. Many platforms have more precise ways to measure wall clock time than time and more precise ways to measure CPU consumption than clock.

I'm using time.h in C++ to measure the timing of a function. clock_t t = clock(); someFunction(); printf("\nTime taken: %.4fs\n", (float)(clock() - t)/CLOCKS_PER_SEC ...

Apr 30, 2015 · How can I create an accurate timer? Use the Date object instead to get the (millisecond-)accurate, current time. Then base your logic on the current time value, instead of counting how often your callback has been executed. For a simple timer or clock, keep track of the time difference explicitly: