如何衡量Linux下C程序的实际执行时间？ [英] How to measure the ACTUAL execution time of a C program under Linux?

问题描述

我知道这个问题可能已经被普遍问过，但似乎大多数的这些问题都是关于的过去的时间（基于挂钟）一片的code。在的过去的一块code的时间是不可能等于的实际的执行时间，其他进程可能会期间执行的过去的感兴趣的code的时间。

我用的getrusage（）来获取进程的用户时间和系统时间，然后通过计算（用户时间+系统时间）的实际执行时间。我正在我在Ubuntu程序。这里是我的问题：

1. 如何知道自己的getrusage的precision（）？


2. 是否有能提供更高的precision比的getrusage其他方法（）？

解决方案

您可以通过利用的CPU时间功能：

 的#include＆LT;＆time.h中GT; clock_t表示起点，终点;
 双cpu_time_used; 开始=时钟（）;
 ... / *做的工作。 * /
 结束=时钟（）;
 cpu_time_used =（（双）（结束 - 开始））/ CLOCKS_PER_SEC;
 

来源：<一个href=\"http://www.gnu.org/s/hello/manual/libc/CPU-Time.html#CPU-Time\">http://www.gnu.org/s/hello/manual/libc/CPU-Time.html#CPU-Time

这样的话，你算CPU蜱或指令的实际量由CPU在工作的过程中，从而获得工作时间的实际数量。

I know this question may have been commonly asked before, but it seems most of those questions are regarding the elapsed time (based on wall clock) of a piece of code. The elapsed time of a piece of code is unlikely equal to the actual execution time, as other processes may be executing during the elapsed time of the code of interest.

I used getrusage() to get the user time and system time of a process, and then calculate the actual execution time by (user time + system time). I am running my program on Ubuntu. Here are my questions:

1. How do I know the precision of getrusage()?
2. Are there other approaches that can provide higher precision than getrusage()?

解决方案

You can check the real CPU time of a process on linux by utilizing the CPU Time functionality of the kernel:

 #include <time.h>

 clock_t start, end;
 double cpu_time_used;

 start = clock();
 ... /* Do the work. */
 end = clock();
 cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;

Source: http://www.gnu.org/s/hello/manual/libc/CPU-Time.html#CPU-Time

That way, you count the CPU ticks or the real amount of instructions worked upon by the CPU on the process, thus getting the real amount of work time.

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