Is this clock tick suitable on Intel i3?

Question

I adopted online to measure SSE performance.

#ifndef __TIMER_H__
#define __TIMER_H__

#pragma warning (push)
#pragma warning (disable : 4035)    // disable no return value warning

__forceinline  unsigned int GetPentiumTimer()
{
    __asm
    {
        xor   eax,eax             // VC won't realize that eax is modified w/out this
                                  //   instruction to modify the val.
                                  //   Problem shows up in release mode builds
        _emit 0x0F                // Pentium high-freq counter to edx;eax
        _emit 0x31                // only care about low 32 bits in eax

        xor   edx,edx             // so VC gets that edx is modified
    }
}

#pragma warning (pop)

#endif

I did the measurement on my Pentium D E2200 CPU, and it works fine (it shows aligned SSE instructions are faster). But on my i3 CPU I get unaligned instructions faster 70% of the tests.

Do you guys think this clock tick measurement is not suitable for i3 CPU?

Answer 1

QueryPerformanceCounter (on Windows at least) is definitely much better than inline assembly. I can't see any reason to use inline assembly (which will give you problems compiling to x64 on Visual Studio which doesn't support inline assembly) over that function.