CPU usage of particular process

[Rahul Bedarkar]

Hi,

I am trying to write small program to get CPU usage for a particular
process. My logic is to read user, nice, system, idle values from
/proc/stat. Then read user and system time from /proc/<pid>/stat. Then wait
for some time and again read same values. After that I am doing following
calculations
CPU% = (no_of_processor * (process_cpu_usage2-process_cpu_usage1) * 100 ) /
(total_cpu_usage2-total_cpu_usage1)

When I compare my output with top, it looks like correct, but sometimes it
is more than 100. Is my logic correct here ? Please correct me if I am
worng.

Regards,
Rahul
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