如何使用psutil.get_cpu_percent（）？

Question

How to exactly use the function get_cpu_percent()?

My code is:

SDKTestSuite.DijSDK_CalculateFps(int(timeForFPS),int(index),cameraName)
cpuUsage = process.get_cpu_percent()

Here I am calling a Function called SDKTestSuite.DijSDK_CalculateFps() and I am calling get_cpu_percent() to get the CPU usage of this call. I am Calling this function for different inputs, The result is sometimes the CPU usage gives 0.0% which is not expected.

So Am I using the get_cpu_percent in the correct manner? How to exactly use this get_cpu_percent function? Is there any interval parameters vary here?

In the actual definition of this function it just sleeps for the given interval and compares the CPU time, but how does it calculates my functionality call here?

Answer 1

If you read the docs , psutil.cpu_percent will:

Return a float representing the current system-wide CPU utilization as a percentage… When interval is 0.0 or None compares system CPU times elapsed since last call or module import, returning immediately…

I'm pretty sure that's not what you want.

First, if you want to know the CPU usage during a specific call , you have to either (a) call it before and after the function, or (b) call it from another thread or process running in parallel with the call, and for the same time as the call (by passing an interval ).

Second, if you want to know how much CPU time that call is using, as opposed to how much that call plus everything else being done by every program on your computer are using, you're not even calling the right function, so there's no way to get it to do what you want.

And there's nothing in psutil that's designed to do that. The whole point of psutil is that it provides information about your system, and about your program from the "outside" perspective. It doesn't know anything about what functions you ran when.

However, there are things that come with the stdlib that do things like that, like resource.getrusage or the cProfile module. Without knowing exactly what you're trying to accomplish, it's hard to tell you exactly what to do, but maybe if you read those linked docs they'll give you some ideas.

Answer 2

you need psutil

pip install psutil

then

import psutil,os
p = psutil.Process(os.getpid())
print(p.cpu_percent())

Answer 3

os.getpid - this will return the PID of the program running this code. For example, when you run it on pythonw.exe, it will return PID of pythonw.exe. Hence p.get_cpu_percent will return CPU usage of that process.

if you want system wide CPU, psutil.cpu_percent can do the job.

Hope this helps, Cheers!

Answer 4

Thanks all... I got the solution for my query.

>>> p = psutil.Process(os.getpid())
>>> # blocking
>>> p.get_cpu_percent(interval=1)
2.0
>>> # non-blocking (percentage since last call)
>>> p.get_cpu_percent(interval=0)
2.9

Here the interval value matters a lot. The final call will give the usage of cpu in percentage for my actual function call.