cpu utilisation

Moore · 06-24-2006, 10:22 AM

hi

anyone familar with how cpu utilisation is calculated on linux based card.

what is the theory behind it and how it is done using

utime
stime
cutime
cstime

ie. the info that is found in /proc/<pid>/stat

is the measurement done for the card or done for the application running on card.

thank you.

bulliver · 06-24-2006, 09:52 PM

card? What do you mean card?

In 'man proc':

Code:

utime %lu
      The number of jiffies that this process has been scheduled in user mode.
stime %lu
      The number of jiffies that this process has been scheduled in kernel mode.
<etc...>

Here, a jiffy is just a way of saying 'cpu instruction'. Ie: every processor tick (and therefore every interrupt request) causes the jiffies variable to increment by 1.

Moore · 06-25-2006, 09:26 AM

hi.

I'm using the word "card" loosely for a single board computer.
This is running linux os and alot of info is stored in the pseudo filesytem mounted on /proc

so, is this the way utilisation is measured?
are these variables incremented updated constantly in real time?

thanks.