Fastest timing resolution system

Question

What is the fastest timing system a C/C++ programmer can use?

For example:
time() will give the seconds since Jan 01 1970 00:00.
GetTickCount() on Windows wi

Answer 1

I'd suggest that you use the GetSystemTimeAsFileTime API if you're specifically targeting Windows. It's generally faster than GetSystemTime and has the same precision (which is some 10-15 milliseconds - don't look at the resolution); when I did a benchmark some years ago under Windows XP it was somewhere in the range of 50-100 times faster.

The only disadvantage is that you might have to convert the returned FILETIME structures to a clock time using e.g. FileTimeToSystemTime if you need to access the returned times in a more human-friendly format. On the other hand, as long as you don't need those converted times in real-time you can always do this off-line or in a "lazy" fashion (e.g. only convert the time stamps you need to display/process, and only when you actually need them).

QueryPerformanceCounter can be a good choice as others have mentioned, but the overhead can be rather large depending on the underlying hardware support. In my benchmark I mention above QueryPerformanceCounter calls was 25-200 times slower than calls to GetSystemTimeAsFileTime. Also, there are some reliability problems as e.g. reported here.

So, in summary: If you can cope with a precision of 10-15 milliseconds I'd recommend you to use GetSystemTimeAsFileTime. If you need anything better than that I'd go for QueryPerformanceCounter.

Small disclaimer: I haven't performed any benchmarking under later Windows versions than XP SP3. I'd recommend you to do some benchmarking on you own.