Problems with cpu_percent() function is giving wrong information

[manurodig]

Hi I'm trying to evaluate the performance of an algorithm, that helps to analyze images. I need to get the mean and median of execution time, the CPU usage, the RAM memory used etc.

I'm using an iMac,The problem is when I tried to check the percentage of use of the CPU, I noticed that the percentage of CPU was something like this:

100
140
145
197
200
182
340
89
90
99
100
111
1000
11000

But i was checking the task manager in the iMac and always I have the same value, 120 %, 127.7 %, 111, 123, 124, 125 etc.

So I was reading that you can divide that number by the cput_count, In this case:

p = psutil.Process(os.getpid())
cpu=p.cpu_percent() / psutil.cpu_count()

I have 4 cpus, so at the end even if I divide the cpu_percent with the cpu_count, I'm going to get results less than the task manager.

So, I think the function is not calculating in a good way the cpu percentage.

Could you help me or suggest something?

[giampaolo]

Hello. What sleep/interval are you using between calls? For instance, this:

for x in range(100):
     print(p.cpu_percent())

...will give you wrong results because the time between calls is too short. Instead you should do:

for x in range(100):
     print(p.cpu_percent(interval=1))

...or if you don't want to block execution make sure to call p.cpu_percent with some delay between calls.

[kaimast]

How is it possible that the percentage returned is larger than the number of logical cores? I run print(cpu_percent(interval=1.0) / cpu_count()) in a loop on Linux and sometimes get values of >100.