comportamento estranho usando chrono :: high_resolution_clock :: now ()

Question

Jan 31, 2014, 01:19 AM

comportamento estranho usando chrono :: high_resolution_clock :: now ()

Estive pesquisando vários métodos de loop de tempo de jogo, por exemplo. Glenn Fiedler e DeWitter. Achei áreas críticas difíceis de entender devido às minhas próprias limitações de conhecimento em C ++. Com isso, comecei a tentar implementar meu próprio método .... Pensei em uma boa maneira de tentar entender algo sobre esses métodos.

[edit1: Estou usando o CodeBlocks IDE com minGW-w64 (x64-4.8.1-posix-seh-rev5) como compilador]

[edit2: janelas de código e saída alteradas para incluir um terceiro temporizador, QueryPerformanceCounter]

Ao tentar fazer isso, deparei-me com o seguinte problema:

Código mínimo:

#include <chrono>
#include <iostream>
#include <windows.h>
#include <stdio.h>

using namespace std;
using namespace chrono;

LARGE_INTEGER startqpc, stopqpc, li;
double PCFreq = 0.0;


void print()
{
for (int p=0; p<1000000; ) p += 1;  //adjust till ms (steady) returns 1-2ms
}

int main()
{
    for(int x=0; x<200; x += 1)
    {
    steady_clock::time_point start = steady_clock::now();
    auto timePoint1 = chrono::high_resolution_clock::now();

    if(!QueryPerformanceFrequency(&li))
        cout << "QueryPerformanceFrequency failed!\n";
    PCFreq = double(li.QuadPart)/1000.0;
    QueryPerformanceCounter(&startqpc);

    print();

    steady_clock::time_point finish = steady_clock::now();
    auto timePoint2 = chrono::high_resolution_clock::now();
    QueryPerformanceCounter(&stopqpc);
    auto elapsedTime(timePoint2 - timePoint1);
    double diff = (stopqpc.QuadPart - startqpc.QuadPart)/PCFreq;

    cout << "Elapsed time: "
              << duration_cast<milliseconds>(finish - start).count() << "ms (steady)   "
              << chrono::duration_cast<chrono::duration<float, milli >> (elapsedTime).count() << "ms (hires)   "
              << diff << " (qpc) \n";

    }
}

Para fins de comparação, o código acima utiliza dois temporizadores.

No meu PC, a saída é a seguinte:

Elapsed time: 1ms (steady)   0ms (hires)   1.8429 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.8429 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.85152 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   15.6001ms (hires)   1.85557 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.59283 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.25573 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.85072 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84263 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84263 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.85422 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84263 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84263 (qpc)
Elapsed time: 1ms (steady)   15.6001ms (hires)   1.85099 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.31582 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.84964 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.52466 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 2ms (steady)   15.6ms (hires)   2.25169 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84263 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.26974 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84991 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84667 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.89518 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.87874 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.92213 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.87605 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84263 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.03126 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.87659 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.88467 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.24899 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.30316 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23579 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93263 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23552 (qpc)
Elapsed time: 2ms (steady)   15.6ms (hires)   2.42118 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.24522 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23471 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23848 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93425 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.9329 (qpc)
Elapsed time: 1ms (steady)   15.6001ms (hires)   1.85126 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.35355 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23687 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23633 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.2374 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23498 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.85449 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.0097 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.15441 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93263 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93425 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23579 (qpc)
Elapsed time: 2ms (steady)   15.6ms (hires)   2.04554 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.1121 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.01779 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.07222 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.9329 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93425 (qpc)
Elapsed time: 1ms (steady)   15.6001ms (hires)   1.95015 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.95177 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84587 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84533 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.85233 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.88278 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84667 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84533 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.88629 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.8456 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.8588 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.06225 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23633 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93317 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.06009 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84533 (qpc)
Elapsed time: 1ms (steady)   15.6001ms (hires)   1.86284 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93425 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.02803 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.26839 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93398 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.93641 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93371 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93344 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.9329 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.02345 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.08731 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.9356 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93398 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.09 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93371 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.03072 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.19213 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.85287 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.9321 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93344 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93317 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93344 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93263 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.42711 (qpc)
Elapsed time: 1ms (steady)   15.6001ms (hires)   1.9418 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.9356 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.08947 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.9329 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93614 (qpc)
Elapsed time: 2ms (steady)   15.6ms (hires)   2.27702 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93614 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93317 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.08974 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.92698 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93317 (qpc)
Elapsed time: 2ms (steady)   15.6ms (hires)   2.09054 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.96066 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.96093 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.8456 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.8456 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.8456 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84533 (qpc)
Elapsed time: 1ms (steady)   15.6001ms (hires)   1.91835 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.8456 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84587 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.8456 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.85233 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93317 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93317 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.23552 (qpc)
Elapsed time: 1ms (steady)   15.6ms (hires)   1.93102 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.07033 (qpc)
Elapsed time: 2ms (steady)   0ms (hires)   2.09405 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.9329 (qpc)
Elapsed time: 1ms (steady)   0ms (hires)   1.93263 (qpc)

Process returned 0 (0x0)   execution time : 0.484 s
Press any key to continue.

Usandoduration_cast<microseconds>(finish - start).count()/1000.0 para o relógio constante, vemos o seguinte: -

Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84263 (qpc)
Elapsed time: 1.843ms (steady)   0ms (hires)   1.84317 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.846ms (steady)   0ms (hires)   1.84694 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.8456 (qpc)
Elapsed time: 1.877ms (steady)   0ms (hires)   1.87685 (qpc)
Elapsed time: 1.916ms (steady)   15.6ms (hires)   1.9162 (qpc)
Elapsed time: 1.906ms (steady)   0ms (hires)   1.90623 (qpc)
Elapsed time: 1.905ms (steady)   0ms (hires)   1.90515 (qpc)
Elapsed time: 1.909ms (steady)   0ms (hires)   1.90919 (qpc)
Elapsed time: 1.905ms (steady)   0ms (hires)   1.90542 (qpc)
Elapsed time: 1.905ms (steady)   0ms (hires)   1.90488 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.943ms (steady)   15.6ms (hires)   1.94287 (qpc)
Elapsed time: 1.872ms (steady)   0ms (hires)   1.87281 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.846ms (steady)   15.6001ms (hires)   1.8464 (qpc)
Elapsed time: 1.875ms (steady)   0ms (hires)   1.87497 (qpc)
Elapsed time: 2.033ms (steady)   0ms (hires)   2.03449 (qpc)
Elapsed time: 1.922ms (steady)   0ms (hires)   1.92293 (qpc)
Elapsed time: 1.922ms (steady)   0ms (hires)   1.92293 (qpc)
Elapsed time: 1.926ms (steady)   0ms (hires)   1.92698 (qpc)
Elapsed time: 2.004ms (steady)   15.6ms (hires)   2.00485 (qpc)
Elapsed time: 1.847ms (steady)   0ms (hires)   1.84748 (qpc)
Elapsed time: 1.847ms (steady)   0ms (hires)   1.84748 (qpc)
Elapsed time: 1.848ms (steady)   0ms (hires)   1.84856 (qpc)
Elapsed time: 1.849ms (steady)   0ms (hires)   1.84937 (qpc)
Elapsed time: 2.299ms (steady)   0ms (hires)   2.29938 (qpc)
Elapsed time: 3.497ms (steady)   15.6ms (hires)   3.49664 (qpc)
Elapsed time: 3.528ms (steady)   0ms (hires)   3.52843 (qpc)
Elapsed time: 2.299ms (steady)   0ms (hires)   2.29857 (qpc)
Elapsed time: 1.849ms (steady)   0ms (hires)   1.84937 (qpc)
Elapsed time: 1.848ms (steady)   0ms (hires)   1.84856 (qpc)
Elapsed time: 1.848ms (steady)   0ms (hires)   1.84856 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84263 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84263 (qpc)
Elapsed time: 1.854ms (steady)   0ms (hires)   1.85395 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.843ms (steady)   0ms (hires)   1.84371 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.8429 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.843ms (steady)   0ms (hires)   1.8429 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.861ms (steady)   0ms (hires)   1.86123 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 2.058ms (steady)   0ms (hires)   2.05848 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.881ms (steady)   0ms (hires)   1.88144 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.843ms (steady)   0ms (hires)   1.84371 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84209 (qpc)
Elapsed time: 1.896ms (steady)   0ms (hires)   1.89653 (qpc)
Elapsed time: 1.842ms (steady)   0ms (hires)   1.84236 (qpc)
Elapsed time: 1.843ms (steady)   0ms (hires)   1.84398 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.886ms (steady)   0ms (hires)   1.88656 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.85ms (steady)   15.6ms (hires)   1.85099 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.848ms (steady)   15.6001ms (hires)   1.84883 (qpc)
Elapsed time: 2.066ms (steady)   0ms (hires)   2.06683 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.888ms (steady)   0ms (hires)   1.88817 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.853ms (steady)   15.6ms (hires)   1.85341 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 2.056ms (steady)   0ms (hires)   2.05605 (qpc)
Elapsed time: 1.88ms (steady)   0ms (hires)   1.8809 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.882ms (steady)   0ms (hires)   1.88224 (qpc)
Elapsed time: 1.849ms (steady)   15.6ms (hires)   1.85018 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 2.243ms (steady)   0ms (hires)   2.24333 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.849ms (steady)   15.6ms (hires)   1.85018 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 2.109ms (steady)   0ms (hires)   2.10914 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84533 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 2.006ms (steady)   0ms (hires)   2.00647 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.852ms (steady)   15.6ms (hires)   1.8526 (qpc)
Elapsed time: 2.534ms (steady)   0ms (hires)   2.53463 (qpc)
Elapsed time: 2.368ms (steady)   0ms (hires)   2.3681 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84533 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84533 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.853ms (steady)   15.6ms (hires)   1.85368 (qpc)
Elapsed time: 1.843ms (steady)   0ms (hires)   1.84371 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84533 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.852ms (steady)   15.6ms (hires)   1.85233 (qpc)
Elapsed time: 1.849ms (steady)   0ms (hires)   1.8491 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84587 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.891ms (steady)   15.6001ms (hires)   1.89168 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.846ms (steady)   0ms (hires)   1.84587 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires),   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.846ms (steady)   15.6ms (hires)   1.8464 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84587 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.848ms (steady)   15.6ms (hires)   1.84829 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.8456 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.846ms (steady)   15.6ms (hires)   1.84614 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.8456 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84506 (qpc)
Elapsed time: 1.872ms (steady)   15.6001ms (hires)   1.87281 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84452 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84587 (qpc)
Elapsed time: 1.844ms (steady)   0ms (hires)   1.84425 (qpc)
Elapsed time: 1.845ms (steady)   0ms (hires)   1.84479 (qpc)

Process returned 0 (0x0)   execution time : 0.499 s
Press any key to continue

Observe como o relógio de alta resolução varia entre 0 e 15,6ms e observe a comparação de relógio constante.

O problema que tenho é que, se eu implementasse um loop de jogo em tempo fixo, em que o código update () atualize as posições da entidade em exatamente 1000/60 (60 ciclos de atualização por segundo), ou seja, a cada 16.666etc ms - isso é muito próximo ao valor de flutuação do temporizador de contratações retornado! O problema real é que, se eu também implementar um acumulador para acomodar os tempos de quadro do loop do jogo abaixo de 1000 / 60ms e qualquer restante após a atualização (), o loop de atualização será inserido mais cedo - e em pontos de tempo irregulares - do que deveria.

Existe um problema com o código mínimo acima e, se não, devo me preocupar com isso para qualquer implementação adequada em horário fixo? Além disso, e se relevante, existe alguma maneira de isolar um programa / thread para que não seja interrompido pelo IRQ do sistema ou outros eventos de pesquisa? Suponho que o temporizador de contratações esteja sujeito a essas interrupções.