问题描述
一个简单的问题：
这是QueryPerformanceFrequency的单位？
赫兹（每秒蜱）？
Which is the QueryPerformanceFrequency unit?Hz (ticks per second)?
非常感谢你，
布鲁诺
Thank you very much,Bruno
推荐答案
Q：QueryPerformanceFrequency的单位
Q: Units of QueryPerformanceFrequency?
答：千赫兹（Hz的不）
A: KILO-HERTZ (NOT Hz)
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我的研究表明，这两个计数器和频率都在多斤，千时钟滴答和千赫！
My research indicates that both Counters and Freq are in KILOs, KILO-clock-ticks and KILO-HERTZ!
计数器注册千点击数（KLICKS）和频率是无论是在kHz或我是可悲的降频。当您Clock_Frequency划分Clock_Ticks，K的点击/（K 的点击* ^秒-1），一切都抹了，除了秒钟。
The counters register KILO-Clicks (KLICKS) and the freq is either in kHz or I am woefully UnderClocked. When you divide the Clock_Ticks by Clock_Frequency, kclicks/(kclicks*sec^-1), everything wipes out except for seconds.
下面是剥离只是要领一个例子C程序：
Here is an example C program stripped to just the essentials:
#include "stdio.h"
#include <windows.h> // Needed for LARGE_INTEGER
// gcc cpu.freq.test.c -o cft.exe
// cft.exe -> Sleep d_KLICKS=3417790, d_time=0.999182880 sec, CPU_Freq=3420585 KILO-Hz
void main(int argc, char *argv[]) {
// Clock KILO-ticks start, end, CPU_Freq in kHz. KILOs cancel
LARGE_INTEGER sklick, eklick, cpu_khz;
double delta_time; // Expected time in SECONDS. All units above are k.
QueryPerformanceFrequency(&cpu_khz); // Gets clock KILO-tics, Klicks/sec
QueryPerformanceCounter(&sklick); // Capture cpu Start Klicks
Sleep(1000); // Sleep 1000 MILLI-seconds
QueryPerformanceCounter(&eklick); // Capture cpu End Klicks
delta_time = (eklick.QuadPart-sklick.QuadPart) / (double)cpu_khz.QuadPart;
printf("Sleep d_KLICKS=%lld, d_time=%4.9lf sec, CPU_Freq=%lld KILO-Hz\n",
eklick.QuadPart-sklick.QuadPart, delta_time, cpu_khz.QuadPart);
}
这实际上编译！正在运行...
It actually compiles! Running...
Sleep d_KLICKS=3418803, d_time=0.999479036 sec, CPU_Freq=3420585 KILO-Hz
该CPU频率读取3420585或3.420585E6或3.4 M-赫兹？ ＆LT;！ - MEGA-HURTS哎唷
The CPU freq reads 3420585 or 3.420585E6 or 3.4 M-Hertz? <- MEGA-HURTS !OUCH!
CPU的实际频率为3.4兆基洛Hz或3.4GHz的
The actual CPU freq is 3.4 Mega-Kilo-Hz or 3.4 GHz
微软似乎混淆（有些东西永远不会改变）：
的
microsoft appears to be confused (some things Never Change):https://msdn.microsoft.com/en-us/library/windows/desktop/dn553408%28v=vs.85%29.aspx
QueryPerformanceFrequency(&Frequency);
QueryPerformanceCounter(&StartingTime);
// Activity to be timed
QueryPerformanceCounter(&EndingTime);
ElapsedMicroseconds.QuadPart = EndingTime.QuadPart - StartingTime.QuadPart;
// We now have the elapsed number of ticks, along with the
// number of ticks-per-second.
已发生滴答的第1秒的人数以百万计，也许是数十亿，因此不会UNIT-CPU时钟蜱但基洛CPU时钟蜱
The number of "elapsed ticks" in 1 second is in the MILLIONS, NOT BILLIONS so they are NOT UNIT-CPU-CLOCK-TICKS but KILO-CPU-CLOCK-TICKS
相同的off-by-3的订单数量级的错误FREQ：340万是不是滴答每秒，但千蜱每秒。
Same off-by-3-orders-of-magnitude error for FREQ: 3.4 MILLION is not "ticks-per-second" but THOUSAND-ticks-per-second.
只要你把一个接其他的？点击取消以秒为结果。如果一个人是如此愚蠢的把他们的文档毫秒，并尝试使用在其他一些计算自己的滴答每秒，你会清盘关闭的1000或约1 standard_ms_error一个因素！
As long as you divide one by the other, the ?clicks cancel with a result in seconds. If one were so fatuous as to take ms at their document and try to use their "ticks-per-second" in some other calculation, you would wind up off by a factor of 1000 or ~1 standard_ms_error!
也许我们应该叫海因里希检查他的单位？哎呀！ 153年为时已晚。 （
Perhaps we should call Heinrich in to check HIS units? Oops! 153 years too late. :(
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