Profile CPU time usage

cpu-time-profile.cpp

#include <stdio.h>

#if defined(__i386__)

static __inline__ unsigned long long rdtsc(void)
{
	unsigned long long int x;
	__asm__ volatile (".byte 0x0f, 0x31" : "=A" (x));
	return x;
}

#elif defined(__x86_64__)

static __inline__ unsigned long long rdtsc(void)
{
	unsigned hi, lo;
	__asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
	return ( (unsigned long long)lo)|( ((unsigned long long)hi)<<32 );
}

#endif

int main () {
	unsigned long long last = rdtsc();
	for (;;) {
		unsigned long long cur = rdtsc();
		unsigned long long diff = cur - last;
		if (diff > (1<<20)) // 1M Cycle
			printf("Missing %d cycles\n", diff);
		last = cur;
	}
}