在Linux中一个进程的计算CPU使用率 [英] Calculating CPU usage of a process in Linux

问题描述

我希望通过编程[用C]在Linux中给定的进程ID计算CPU使用率％。

I want to programatically [in C] calculate CPU usage % for a given process ID in Linux.

我们怎样才能获得实时的CPU使用率％，对于一个给定的过程??

How can we get the realtime CPU usage % for a given process ??

要使它进一步明确 -

To make it further clear -

• 我应该能够确定用于提供进程ID或处理的CPU使用率。


• 这个过程不需要子进程。


• 我想在'C'语言的解决方案。

推荐答案

您需要从的/ proc /＆LT解析出数据; PID＆GT; / STAT 。这是第几个字段（从文档/文件系统/ proc.txt 在你的内核源代码）：

You need to parse out the data from /proc/<PID>/stat. These are the first few fields (from Documentation/filesystems/proc.txt in your kernel source):

Table 1-3: Contents of the stat files (as of 2.6.22-rc3)
..............................................................................
 Field          Content
  pid           process id
  tcomm         filename of the executable
  state         state (R is running, S is sleeping, D is sleeping in an
                uninterruptible wait, Z is zombie, T is traced or stopped)
  ppid          process id of the parent process
  pgrp          pgrp of the process
  sid           session id
  tty_nr        tty the process uses
  tty_pgrp      pgrp of the tty
  flags         task flags
  min_flt       number of minor faults
  cmin_flt      number of minor faults with child's
  maj_flt       number of major faults
  cmaj_flt      number of major faults with child's
  utime         user mode jiffies
  stime         kernel mode jiffies
  cutime        user mode jiffies with child's
  cstime        kernel mode jiffies with child's

您在 UTIME 很可能和/或 STIME 。你还需要读 CPU 从的/ proc / STAT ，它看起来像行：

You're probably after utime and/or stime. You'll also need to read the cpu line from /proc/stat, which looks like:

cpu  192369 7119 480152 122044337 14142 9937 26747 0 0

这告诉你，在各个类别中使用，以jiffies为单位的累计CPU时间。你需要采取在这条线的值的总和来获得 TIME_TOTAL 的措施。

This tells you the cumulative CPU time that's been used in various categories, in units of jiffies. You need to take the sum of the values on this line to get a time_total measure.

同时读取 UTIME 和 STIME 为你感兴趣的，读的过程中 TIME_TOTAL 从的/ proc / STAT 。然后睡了一秒钟左右，然后再阅读它们。现在可以计算过程的CPU使用率在采样时间，用

Read both utime and stime for the process you're interested in, and read time_total from /proc/stat. Then sleep for a second or so, and read them all again. You can now calculate the CPU usage of the process over the sampling time, with:

user_util = 100 * (utime_after - utime_before) / (time_total_after - time_total_before);
sys_util = 100 * (stime_after - stime_before) / (time_total_after - time_total_before);

请有意义吗？

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