Question

I know QueryPerformanceCounter() can be used for timing functions. I want to know:

1-Can I increase the resolution of the timer by over-clocking the CPU (so it ticks faster)?

2-Basically what makes some timers more precise than others, (e.g, QueryPerformanceCounter() is more precise as compared to GetTickCount())? If there is single crystal oscillator on the motherboard , why some timers are slower as compared to others?

Answer 1

1. QueryPerformanceCounter has very high resolution – normally less than one nanosecond. I don’t see why you’d like to increase it. Overclocking will increase it, but it seems like a very weak reason for overclocking.

2. QueryPerformanceCounter is very accurate, but somewhat expensive and not very convenient.
   a. It’s expensive because it uses the expensive rdtsc instruction. Faster timers can just read an integer from memory. This integer needs to be updated, and we don’t want to do it too often (1000 times a second is reasonable), so we get a very cheap timer, with low precision. That’s basically GetTickCount.
   b. It’s inconvenient because it uses units which change between computers. Sometimes it will be nanoseconds, sometimes half-nano, or other values. It makes it harder to calculate with.
   a. Another source of inconvenience is that it returns very large numbers, which may overflow when you try to do math with them, so you need to be careful.