Hi,

It seems to me that using vmstat, prstat or top at the same moment, the CPU Usage results are different on those tools. Could somebody explain me why ? What is exactly calculated in each tool ?
In parrallel, I have a another tool (home made), which calculates the CPU Usage by parsing all the /proc directory and getting the CPU of each process through ioctl (PIOCPSINFO, pr_pctcpu). This tool gives another result ! Why ?

Thanks for your help

Ed

Ed,

I don't have an answer to your question, but I saw something in your question that interested me. You said you have a homemade tool to calculate CPU usage etc. I am trying to do almost exactly the same thing that your tool does, only I don't want a total cpu usage, just the usage by a process and all its child processes. I know I can do this using ps or top, but they take too long. How does your tool work? Can you share it? BTW, I'm using Red Hat Linux 7.2. Thanks.

Paul