当psutil.cpu_percent被调用时，iowait时间算数吗？

Question

我想知道iowait时间是否在psutil.cpu_percent()中计算，所以编写如下代码来测试

#cat test.py
import os
import psutil
import time


p = psutil.Process(os.getpid())


start = time.time()
times_before_workload = p.cpu_times()
# this function return cpu_percent between two call. so we have to call it once before workload
percent_before_workload = p.cpu_percent()  


# I call f open/close many times and read from the file 
# hoping cpu will spent time on both user system and iowait

c = 1000
while c:
    f = open('/tmp/big_text')
    content = f.read(10240)
    f.close()
    c -= 1

end = time.time()
percent_after_workload = p.cpu_percent()


times_after_workload = p.cpu_times()
user_seconds = times_after_workload.user - times_before_workload.user
system_seconds = times_after_workload.system - times_before_workload.system
iowait_seconds = times_after_workload.iowait - times_before_workload.iowait

# if cpu percent == user_percent + system_percent + iowait_percent then it means yes. iowait are counted

print 'user_percent %s' % round(user_seconds / (end - start) * 100, 2)
print 'system_percent %s' % round(system_seconds / (end - start) * 100, 2)
print 'iowait_percent %s' % round(iowait_seconds / (end - start) * 100, 2)
print 'percent %s' % percent_after_workload

这是输出

#python test.py
user_percent 67.06
system_percent 67.06
iowait_percent 0.0
percent 134.8

iowait是0，所以仍然无法验证。所以问题是

1. iowait计算cpu百分比吗？
2. 怎样才能做到这一点？(没有零)

Answer 1

1. 不，不算cpu百分比。
2. 运行vmtouch，在循环的每次迭代开始时从内存中删除页面。

您可能需要安装vmtouch：

apt update
apt install vmtouch

在Python中运行vmtouch：

import subprocess

subprocess.run(['vmtouch', '-e', '/tmp/big_text'], stdout=subprocess.DEVNULL)

参考资料：为什么读取文件是零？