making mistake in inline assembler in gcc [duplicate]

Answer 1

This will store the result in value. Combining the results takes extra cycles, so the number of cycles between calls to this code will be a few less than the difference in results.

unsigned int hi,lo;
unsigned long long value;
asm (
    "cpuid\n\t"
    "rdtsc"
    : "d" (hi), "a" (lo)
);
value = (((unsigned long long)hi) << 32) | lo;