Re: [boost] Request: RDTSC

9 Jun 2008

      dherring@ll.mit.edu wrote:
...
The CPU timestamp counter is a high-resolution clock source useful for 
profiling code or controlling tight timing loops.  AMD/Intel CPUs support 
this via the RDTSC opcode, and other CPUs often provide similar 
functionality.
Apparently MS compilers support an __rdtsc() intrinsic, but I couldn't 
find one for gcc.
MSVS 8.0 and higher have the __rdtsc intrinsic.

Om earlier versions of MSVC you can use the following inline assembler:

inline uint64_t clockCycleCount()
{
	uint64_t ccc;
	__asm {
		cpuid		// serialize processor
		rdtsc		// read time stamp counter
		mov dword ptr [ccc + 0], eax
		mov dword ptr [ccc + 4], edx
	}
	return ccc;
}

I agree that a platform independent version would be useful.

--Johan Råde