准确计算Linux中以百分比给出的CPU使用率？

4 回答

• 54

  根据撰写本文时的htop源代码，我的假设看起来有效：

  （见 void ProcessList_scan(ProcessList* this) 函数ProcessList.c）

  // Guest time is already accounted in usertime
  usertime = usertime - guest;                     # As you see here, it subtracts guest from user time
  nicetime = nicetime - guestnice;                 # and guest_nice from nice time
  // Fields existing on kernels >= 2.6
  // (and RHEL's patched kernel 2.4...)
  idlealltime = idletime + ioWait;                 # ioWait is added in the idleTime
  systemalltime = systemtime + irq + softIrq;
  virtalltime = guest + guestnice;
  totaltime = usertime + nicetime + systemalltime + idlealltime + steal + virtalltime;
  

  因此，从 /proc/stat 第一行中列出的字段:(参见第1.1节documentation）

  user    nice   system  idle      iowait irq   softirq  steal  guest  guest_nice
  cpu  74608   2520   24433   1117073   6176   4054  0        0      0      0
  

  从算法上讲，我们可以计算CPU使用百分比，如：

  PrevIdle = previdle + previowait
  Idle = idle + iowait
  
  PrevNonIdle = prevuser + prevnice + prevsystem + previrq + prevsoftirq + prevsteal
  NonIdle = user + nice + system + irq + softirq + steal
  
  PrevTotal = PrevIdle + PrevNonIdle
  Total = Idle + NonIdle
  
  # differentiate: actual value minus the previous one
  totald = Total - PrevTotal
  idled = Idle - PrevIdle
  
  CPU_Percentage = (totald - idled)/totald
  

  回复于 2024-04-19T03:28:09+08:00
• 7

  以下是基于Vangelis答案的bash脚本 . 它产生如下输出：

  total 49.1803
  cpu0 14.2857
  cpu1 100
  cpu2 28.5714
  cpu3 100
  cpu4 30
  cpu5 25
  

  创建一个名为 get_cpu_usage.sh 的文件

  使用以下命令运行它： bash get_cpu_usage.sh 0.2

  参数是要测量的秒数 . 在这种情况下，它是200毫秒 .

  内容如下：

  #!/bin/sh
  
  sleepDurationSeconds=$1
  
  previousDate=$(date +%s%N | cut -b1-13)
  previousStats=$(cat /proc/stat)
  
  sleep $sleepDurationSeconds
  
  currentDate=$(date +%s%N | cut -b1-13)
  currentStats=$(cat /proc/stat)    
  
  cpus=$(echo "$currentStats" | grep -P 'cpu' | awk -F " " '{print $1}')
  
  for cpu in $cpus
  do
      currentLine=$(echo "$currentStats" | grep "$cpu ")
      user=$(echo "$currentLine" | awk -F " " '{print $2}')
      nice=$(echo "$currentLine" | awk -F " " '{print $3}')
      system=$(echo "$currentLine" | awk -F " " '{print $4}')
      idle=$(echo "$currentLine" | awk -F " " '{print $5}')
      iowait=$(echo "$currentLine" | awk -F " " '{print $6}')
      irq=$(echo "$currentLine" | awk -F " " '{print $7}')
      softirq=$(echo "$currentLine" | awk -F " " '{print $8}')
      steal=$(echo "$currentLine" | awk -F " " '{print $9}')
      guest=$(echo "$currentLine" | awk -F " " '{print $10}')
      guest_nice=$(echo "$currentLine" | awk -F " " '{print $11}')
  
      previousLine=$(echo "$previousStats" | grep "$cpu ")
      prevuser=$(echo "$previousLine" | awk -F " " '{print $2}')
      prevnice=$(echo "$previousLine" | awk -F " " '{print $3}')
      prevsystem=$(echo "$previousLine" | awk -F " " '{print $4}')
      previdle=$(echo "$previousLine" | awk -F " " '{print $5}')
      previowait=$(echo "$previousLine" | awk -F " " '{print $6}')
      previrq=$(echo "$previousLine" | awk -F " " '{print $7}')
      prevsoftirq=$(echo "$previousLine" | awk -F " " '{print $8}')
      prevsteal=$(echo "$previousLine" | awk -F " " '{print $9}')
      prevguest=$(echo "$previousLine" | awk -F " " '{print $10}')
      prevguest_nice=$(echo "$previousLine" | awk -F " " '{print $11}')    
  
      PrevIdle=$((previdle + previowait))
      Idle=$((idle + iowait))
  
      PrevNonIdle=$((prevuser + prevnice + prevsystem + previrq + prevsoftirq + prevsteal))
      NonIdle=$((user + nice + system + irq + softirq + steal))
  
      PrevTotal=$((PrevIdle + PrevNonIdle))
      Total=$((Idle + NonIdle))
  
      totald=$((Total - PrevTotal))
      idled=$((Idle - PrevIdle))
  
      CPU_Percentage=$(awk "BEGIN {print ($totald - $idled)/$totald*100}")
  
      if [[ "$cpu" == "cpu" ]]; then
          echo "total "$CPU_Percentage
      else
          echo $cpu" "$CPU_Percentage
      fi
  done
  

  回复于 2024-04-19T03:28:09+08:00
• 5

  嘿，我也在研究这个主题，发现这个主题非常有用 . 我使用Vangelis Tasoulas公式为此编写一个小的python脚本 . 附件是我的问题的Python代码 . 它每秒加载每个cpu_id的cpu使用量 . 也许它也有助于其他人 . 欢迎提出意见/建议:-)

  #!/usr/bin/python 
  # -*- coding: utf-8 -*-
  
  '''
  Created on 04.12.2014
  
  @author: plagtag
  '''
  from time import sleep
  import sys
  
  class GetCpuLoad(object):
      '''
      classdocs
      '''
  
  
      def __init__(self, percentage=True, sleeptime = 1):
          '''
          @parent class: GetCpuLoad
          @date: 04.12.2014
          @author: plagtag
          @info: 
          @param:
          @return: CPU load in percentage
          '''
          self.percentage = percentage
          self.cpustat = '/proc/stat'
          self.sep = ' ' 
          self.sleeptime = sleeptime
  
      def getcputime(self):
          '''
          http://stackoverflow.com/questions/23367857/accurate-calculation-of-cpu-usage-given-in-percentage-in-linux
          read in cpu information from file
          The meanings of the columns are as follows, from left to right:
              0cpuid: number of cpu
              1user: normal processes executing in user mode
              2nice: niced processes executing in user mode
              3system: processes executing in kernel mode
              4idle: twiddling thumbs
              5iowait: waiting for I/O to complete
              6irq: servicing interrupts
              7softirq: servicing softirqs
  
          #the formulas from htop 
               user    nice   system  idle      iowait irq   softirq  steal  guest  guest_nice
          cpu  74608   2520   24433   1117073   6176   4054  0        0      0      0
  
  
          Idle=idle+iowait
          NonIdle=user+nice+system+irq+softirq+steal
          Total=Idle+NonIdle # first line of file for all cpus
  
          CPU_Percentage=((Total-PrevTotal)-(Idle-PrevIdle))/(Total-PrevTotal)
          '''
          cpu_infos = {} #collect here the information
          with open(self.cpustat,'r') as f_stat:
              lines = [line.split(self.sep) for content in f_stat.readlines() for line in content.split('\n') if line.startswith('cpu')]
  
              #compute for every cpu
              for cpu_line in lines:
                  if '' in cpu_line: cpu_line.remove('')#remove empty elements
                  cpu_line = [cpu_line[0]]+[float(i) for i in cpu_line[1:]]#type casting
                  cpu_id,user,nice,system,idle,iowait,irq,softrig,steal,guest,guest_nice = cpu_line
  
                  Idle=idle+iowait
                  NonIdle=user+nice+system+irq+softrig+steal
  
                  Total=Idle+NonIdle
                  #update dictionionary
                  cpu_infos.update({cpu_id:{'total':Total,'idle':Idle}})
              return cpu_infos
  
      def getcpuload(self):
          '''
          CPU_Percentage=((Total-PrevTotal)-(Idle-PrevIdle))/(Total-PrevTotal)
  
          '''
          start = self.getcputime()
          #wait a second
          sleep(self.sleeptime)
          stop = self.getcputime()
  
          cpu_load = {}
  
          for cpu in start:
              Total = stop[cpu]['total']
              PrevTotal = start[cpu]['total']
  
              Idle = stop[cpu]['idle']
              PrevIdle = start[cpu]['idle']
              CPU_Percentage=((Total-PrevTotal)-(Idle-PrevIdle))/(Total-PrevTotal)*100
              cpu_load.update({cpu: CPU_Percentage})
          return cpu_load
  
  
  if __name__=='__main__':
      x = GetCpuLoad()
      while True:
          try:
              data = x.getcpuload()
              print data
          except KeyboardInterrupt:
  
              sys.exit("Finished")
  

  回复于 2024-04-19T03:28:09+08:00
• 1

  idnt.net对如何使用/ proc / stat cpu数据有很好的描述，包括用于提取cpu的bash脚本和行的描述 . 我只是想在这里链接它，因为我发现它很有 Value .

  回复于 2024-04-19T03:28:09+08:00