нечетное поведение с использованием chrono :: high_resolution_clock :: now()

Question

Я изучал различные методы цикла синхронизации времени, например. Гленн Фидлер и Де Виттер. Я обнаружил, что критические области трудно понять из-за моих собственных ограничений на знание C++. С этим я приступил к попытке реализовать свой собственный метод ... Я думал, что хороший способ попытаться понять что-то об этих методах.

[edit1: Я использую CodeBlocks IDE с MinGW-w64 (x64-4.8.1-POSIX-SEH-rev5) в качестве составителя]

[edit2: код и выходные окна с поправками включить 3-ю таймер, QueryPerformanceCounter]

в попытке достичь этого я наткнулся на следующий вопрос:

Минимальный код:

#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"; 

    } 
} 

для сравнения, выше трески e использует два таймера.

На моем компьютере выход из этого заключается в следующем:

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. 

Использование duration_cast<microseconds>(finish - start).count()/1000.0 для steady_clock мы видим следующее: -

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) 
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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) 
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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) 
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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) 
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Elapsed time: 1.845ms (steady) 0ms (hires) 1.84506 (qpc) 
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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 

Обратите внимание, как высокое разрешение часы колеблется между 0 и 15,6 мс и обратите внимание на сравнение с установившимся временем.

Проблема заключается в том, что если бы я должен был реализовать цикл игры с фиксированным сроком, в котором код update() обновляет позиции объектов точно в 1000/60 (60 циклов обновления в секунду), то есть каждые 16.666etc мс - то это очень близко к возвращаемому таймеру, зависящему от количества часов! Реальная проблема заключается в том, что если я также реализую аккумулятор для того, чтобы учесть время цикла фрейма, равное 1000/60 мс, и любое оставшееся после завершения обновления(), цикл обновления вводится раньше - и в нерегулярные моменты времени - чем должно.

Есть ли проблема с минимальным кодом выше, а если нет, должен ли я быть заинтересован в этом для какой-либо надлежащей реализации фиксированного времени? Кроме того, и, если необходимо, есть ли способ изолировать программу/поток, чтобы он не прерывался системой IRQ или другими событиями опроса? Я предполагаю, что таймер найма может подвергаться таким перерывам.

Answer 1

В вашей стандартной библиотеке есть ошибка std::chrono.

Я знаю одну такую ​​ошибку в Visual C++, не знаю, какой компилятор вы используете, но если поддержка std::chrono является недавним дополнением, у них могут быть некоторые недостатки.

Если вы используете Visual C++, вы должны знать:

• C++ header's high_resolution_clock does not have high resolution
• steady_clock class and clock() function are non conformant with C++11 and C11 standards