Can I use the "Idle" process to figure out why my processor utilization has been?

  • Thread starter Thread starter john
  • Start date Start date
J

john

I don't want to know what the CPU utilization is right now. I want to
get the average utilization over the last, for example, hour. So I
came up with a method where I would get a Process object representing
the "Idle" process. I would figure out what percentage of time the
idle process has been running since my function last was called. Then
the average CPU utilization would be 100 - average idle percentage. I
figure out the average idle percentage by dividing the difference in
TotalProcessorTime by the difference in total time since the function
was called last. Here's the code

DateTime _oldTime;
TimeSpan _oldCPUUsage;

private void CPUUsage()
{
//Find out how much processor has been idle. Usage is 100% -
idle%.
DateTime newTime = DateTime.Now;
TimeSpan newCPUUsage = Process.GetProcessesByName
("Idle")[0].TotalProcessorTime;
double idlePercent =
(newCPUUsage.Subtract(_oldCPUUsage).TotalHours /
newTime.Subtract(_oldTime).TotalHours) * 100;

Debug.WriteLine((100.0 - idlePercent).ToString());
_oldCPUUsage = newCPUUsage;
_oldTime = newTime;
}

It seems to work great some of the time, but not all the time.
Sometimes my CPU usage (100.0 - idlePercent) ends up being negative or
really big (> 100000). So there's got to be something wrong in my
algorithm, but I don't know what. My thinking is that the "idle"
process might not always be an accurate way to get what I think it's
giving me. Any ideas?

Or is there a better way to do what I am trying to do?

thanks

John
 
Use the PerformanceCounters, so just like PerfMon, you can get accurate data
and average it out.
-mike
MVP
 
Use the PerformanceCounters, so just like PerfMon, you can get accurate data
and average it out.
-mike
MVP
Click to expand...

If I use PerformanceCounters, can it return to me the average CPU
usage over the last hour? Or would I have to do a regular sample
(maybe once every 5 seconds) and then average the samples myself? If I
have to take samples and then average them, it will be somewhat
inaccurate (e.g. the usage could change quite a bit in the middle of
my samples). But with the method I proposed in my original post, it
will be completely accurate even if the function runs only once an
hour. The problem is that it occasionally gets crazy results.

thanks.
 
Those are some valid points. In the case that you get crazy results, why
not have it dump all the variables so you could see what went on?
-mike
MVP
 
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