Process\% Processor Time - What is the percentage calculated from?

Question

Hi All,

I'm doing a proactive piece of work, looking at the impact of installing a new agent on a multisession OS (2016) so we can assess how much resource the agent will consume and whether or not this will affect the number of user sessions the server can support.

We have a PerfMon capture with a load of counters captured for a reasonable time period, the one I am looking at specifically is the Process\% Processor Time at the two processes that run for this agent. Looking to understand the Processor resource utilised specifically, memory, disk seem pretty straightforward to work out.

My question is, what is that percentage for Process\% Processor Time calculated from? As you would expect, its a multiprocessor server, with 24 logical cores. I have seen some documentation to suggest that the Process\% Processor Time counter is calculated from 100*No. Cores as the maximum, so in this case 100*24 = 2400%.

Perfmon has shown a total of 4% processor time from the user session process and 13% processor time from the system process for a total of 17% Processor Time. So is this 17% out of 2400% or should I consider it as 17% of the total processor resources available i.e. 17% of total processing resource?

Any clarification welcome! The answer makes a big difference, 17% of total processor time is a lot, 17% out of 2400% measure is not.

Thanks,
Jonathan

Answer 1

Hello

Thank you for your question and reaching out. I can understand you are having query related to Performance monitor of CPU.

% Processor Time is the percentage of elapsed time that the processor spends to execute a non-Idle thread. It is calculated by measuring the percentage of time that the processor spends executing the idle thread and then subtracting that value from 100%. (Each processor has an idle thread that consumes cycles when no other threads are ready to run). This counter is the primary indicator of processor activity, and displays the average percentage of busy time observed during the sample interval.

Reference :

https://social.technet.microsoft.com/wiki/contents/articles/12984.understanding-processor-processor-time-and-process-processor-time.aspx

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Answer 2

Hi,

Thanks for your reply.

I had actually read that article and it was clarity on the following point I was after:

*If you look into the description of the Process (%Processor Time) it looks like
% Processor Time is the percentage of elapsed time that all of process threads used the processor to execution instructions. An instruction is the basic unit of execution in a
computer, a thread is the object that executes instructions, and a process is the object created when a program is run. Code executed to handle some hardware interrupts and trap conditions are included in this count.
Now this Processor time counter under the Process Object gives the amount of CPU this Process is taking individually. This value is calculated over the base line of
(No of Logical CPUS * 100), So this is going to be a calculated over a baselin of more than 100.*

So I was looking for clarity / confirmation that in as an example a 24 core processer setup, is a measured 'process\% processor time' of 17% from a value of 100% total processor resource (all cores), or 17% of 24 cores x 100% = 2400% as this makes a massive difference to the impact of what 17% means :)

Anyone able to confirm if its

17% Processor Time from 100% Total or
17% Processor Time from 2400% Total

Thanks,
Jonathan

Answer 3

I am also looking answers for the same question.

My machines are having 8 logical CPU, so I am expecting a max of 800%. But in some samples for a minute or so, i observed this value going upto 5600%, which is not making any logical sense.

Can someone please help me understand why this can happen and how to interpret this?