如何在不使用PSUtil的情况下获得python 2.7中的CPU使用率

尝试在

Python

中获取CPU使用率，而不使用

PSUtil

我试过以下方法，但它似乎总是报告相同的数字

def getCPUuse():
    return(str(os.popen("top -n1 | awk '/Cpu\(s\):/ {print $2}'").readline().strip(\
)))

print(getCPUuse())

这似乎总是报告3.7%，即使我加载CPU

我也试过以下方法

str(round(float(os.popen('''grep 'cpu ' /proc/stat | awk '{usage=($2+$4)*100/($2+$4+$5)} END {print usage }' ''').readline()),2))

这似乎总是返回5.12。我必须承认，我真的不知道上面所说的是什么。如果我在命令行中输入

grepcpu/proc/stat

，我会得到如下结果

cpu  74429 1 19596 1704779 5567 0 284 0 0 0
cpu0 19596 0 4965 422508 1640 0 279 0 0 0
cpu1 18564 1 4793 427115 1420 0 1 0 0 0
cpu2 19020 0 4861 426916 1206 0 2 0 0 0
cpu3 17249 0 4977 428240 1301 0 2 0 0 0

我猜我的命令没有正确地从上面的输出中提取所有CPU核心的值

---

我的目标是在不使用PSUtil的情况下从我的设备（Raspberry PI）获得总CPU%。该图应该反映操作系统任务管理器中显示的内容。

这并不容易，因为您描述的大多数进程都提供了CPU使用的累积或总平均值

也许您可以尝试使用te

systat

软件包附带的

mpstat

命令

因此，我在以下脚本中使用的步骤是：

要求

mpstat

生成两份报告，一份立即生成，另一份在1秒后生成（

mpstat 12

）

然后我们得到

平均值

行（最后一行）

最后一列是

%idle

列，因此我们使用

awk

我们使用子流程中的

Popen

，但设置

shell=True

接受管道（

|

）选项

我们执行命令（

communicate（）

）

用

条清洁输出

从100中减去（空闲百分比），我们就可以得到使用的值

由于它将休眠

1秒

，因此不要担心它不是即时命令

---

PSUtil、htop、mpstat等所做的是从

/proc/stat

读取以

“cpu”

开头的行（实际上是第一行），然后从该行中的值计算百分比。您可以在

man 5 proc

（搜索“proc/stat”）中找到该行上的值的含义

这也是您提到的grepcpu/proc/stat | awk….命令所做的。但是

/proc/stat

中的值表示自上次启动以来花费的时间！我不确定，也许过了一段时间它们就会卷土重来，但问题是这些数字是在很长一段时间内测量出来的

因此，如果您运行该命令，并在几秒钟（、分钟甚至数小时）后再次运行它，它们不会有太大的变化！这就是为什么你看到它总是返回5.12

像

top

这样的程序记住以前的值，并从新读取的值中减去它们。从结果中可以计算出“活动”百分比，该百分比实际上反映了最近的CPU负载

要在python中尽可能简单地执行类似操作，但不运行外部命令来读取

/proc/stat

并为我们进行计算，我们可以将读取的值存储到一个文件中。下一次运行时，我们可以读回它们，并从新值中减去它们

#!/usr/bin/env python2.7

import os.path

# Read first line from /proc/stat. It should start with "cpu"
# and contains times spent in various modes by all CPU's totalled.
#
with open("/proc/stat") as procfile:
    cpustats = procfile.readline().split()

# Sanity check
#
if cpustats[0] != 'cpu':
    raise ValueError("First line of /proc/stat not recognised")

#
# Refer to "man 5 proc" (search for /proc/stat) for information
# about which field means what.
#
# Here we do calculation as simple as possible:
# CPU% = 100 * time_doing_things / (time_doing_things + time_doing_nothing)
#

user_time = int(cpustats[1])    # time spent in user space
nice_time = int(cpustats[2])    # 'nice' time spent in user space
system_time = int(cpustats[3])  # time spent in kernel space

idle_time = int(cpustats[4])    # time spent idly
iowait_time = int(cpustats[5])    # time spent waiting is also doing nothing

time_doing_things = user_time + nice_time + system_time
time_doing_nothing = idle_time + iowait_time

# The times read from /proc/stat are total times, i.e. *all* times spent
# doing things and doing nothing since last boot.
#
# So to calculate  meaningful CPU % we need to know how much these values
# have *changed*.  So we store them in a file which we read next time the
# script is run.
# 
previous_values_file = "/tmp/prev.cpu"
prev_time_doing_things = 0
prev_time_doing_nothing = 0

try:
    with open(previous_values_file) as prev_file:
        prev1, prev2 = prev_file.readline().split()
    prev_time_doing_things = int(prev1)
    prev_time_doing_nothing = int(prev2)
except IOError:  # To prevent error/exception if file does not exist. We don't care.
    pass   

# Write the new values to the file to use next run
#
with open(previous_values_file, 'w') as prev_file:
    prev_file.write("{} {}\n".format(time_doing_things, time_doing_nothing))

# Calculate difference, i.e: how much the number have changed
#
diff_time_doing_things = time_doing_things - prev_time_doing_things
diff_time_doing_nothing = time_doing_nothing - prev_time_doing_nothing

# Calculate a percentage of change since last run:
#
cpu_percentage = 100.0 * diff_time_doing_things/ (diff_time_doing_things + diff_time_doing_nothing)

# Finally, output the result
#
print "CPU", cpu_percentage, "%"

这是一个与

top

不同的版本，它每秒打印一次CPU使用情况，用变量而不是文件记住以前测量的CPU时间：

#!/usr/bin/env python2.7

import os.path
import time

def get_cpu_times():
    # Read first line from /proc/stat. It should start with "cpu"
    # and contains times spend in various modes by all CPU's totalled.
    #
    with open("/proc/stat") as procfile:
        cpustats = procfile.readline().split()

    # Sanity check
    #
    if cpustats[0] != 'cpu':
        raise ValueError("First line of /proc/stat not recognised")

    # Refer to "man 5 proc" (search for /proc/stat) for information
    # about which field means what.
    #
    # Here we do calculation as simple as possible:
    #
    # CPU% = 100 * time-doing-things / (time_doing_things + time_doing_nothing)
    #

    user_time = int(cpustats[1])    # time spent in user space
    nice_time = int(cpustats[2])    # 'nice' time spent in user space
    system_time = int(cpustats[3])  # time spent in kernel space

    idle_time = int(cpustats[4])    # time spent idly
    iowait_time = int(cpustats[5])    # time spent waiting is also doing nothing

    time_doing_things = user_time + nice_time + system_time
    time_doing_nothing = idle_time + iowait_time

    return time_doing_things, time_doing_nothing


def cpu_percentage_loop():
    prev_time_doing_things = 0
    prev_time_doing_nothing = 0
    while True:  # loop forever printing CPU usage percentage
        time_doing_things, time_doing_nothing = get_cpu_times()
        diff_time_doing_things = time_doing_things - prev_time_doing_things
        diff_time_doing_nothing = time_doing_nothing - prev_time_doing_nothing
        cpu_percentage = 100.0 * diff_time_doing_things/ (diff_time_doing_things + diff_time_doing_nothing)

        # remember current values to subtract next iteration of the loop
        #
        prev_time_doing_things = time_doing_things
        prev_time_doing_nothing = time_doing_nothing

        # Output latest perccentage
        #
        print "CPU", cpu_percentage, "%"

        # Loop delay
        #
        time.sleep(1)

if __name__ == "__main__":
    cpu_percentage_loop()

---

有趣的解决方案。您认为每个样品之间需要多少时间？我想知道是否可以将当前值保留在内存中，以避免写入文件，并在比较之前只休眠指定的时间。当然，top和htop就是这样做的：它们（默认情况下）每1秒刷新一次，并将以前在内存中花费的CPU时间保留1秒。“man 5 proc”表示时间是以秒为单位测量的“大多数体系结构上的1/100秒“。因此，只有当你开始使用短到，比如说，大大短于0.1秒的时间时，它们才开始变得不那么有意义。添加了一个版本的python脚本，该脚本不编写文件，但可以记住以前在变量中的度量值。出色的解决方案，+1我不知道这为什么没有获得足够的升级票！

#!/usr/bin/env python2.7

import os.path
import time

def get_cpu_times():
    # Read first line from /proc/stat. It should start with "cpu"
    # and contains times spend in various modes by all CPU's totalled.
    #
    with open("/proc/stat") as procfile:
        cpustats = procfile.readline().split()

    # Sanity check
    #
    if cpustats[0] != 'cpu':
        raise ValueError("First line of /proc/stat not recognised")

    # Refer to "man 5 proc" (search for /proc/stat) for information
    # about which field means what.
    #
    # Here we do calculation as simple as possible:
    #
    # CPU% = 100 * time-doing-things / (time_doing_things + time_doing_nothing)
    #

    user_time = int(cpustats[1])    # time spent in user space
    nice_time = int(cpustats[2])    # 'nice' time spent in user space
    system_time = int(cpustats[3])  # time spent in kernel space

    idle_time = int(cpustats[4])    # time spent idly
    iowait_time = int(cpustats[5])    # time spent waiting is also doing nothing

    time_doing_things = user_time + nice_time + system_time
    time_doing_nothing = idle_time + iowait_time

    return time_doing_things, time_doing_nothing


def cpu_percentage_loop():
    prev_time_doing_things = 0
    prev_time_doing_nothing = 0
    while True:  # loop forever printing CPU usage percentage
        time_doing_things, time_doing_nothing = get_cpu_times()
        diff_time_doing_things = time_doing_things - prev_time_doing_things
        diff_time_doing_nothing = time_doing_nothing - prev_time_doing_nothing
        cpu_percentage = 100.0 * diff_time_doing_things/ (diff_time_doing_things + diff_time_doing_nothing)

        # remember current values to subtract next iteration of the loop
        #
        prev_time_doing_things = time_doing_things
        prev_time_doing_nothing = time_doing_nothing

        # Output latest perccentage
        #
        print "CPU", cpu_percentage, "%"

        # Loop delay
        #
        time.sleep(1)

if __name__ == "__main__":
    cpu_percentage_loop()