In freebsd-questions Digest, Vol 300, Issue 11, Message: 8 On Fri, 5 Mar 2010 16:58:20 -0600 Dan Nelson <[email protected]> wrote: > In the last episode (Mar 05), Peter Steele said: > > > What's the proper way to calculate kernel/user/idle time? I know the raw > > values come from sysctl kern.cp_time, but these values need to be > > "massaged" based on the number of CPUs and so on. Can someone explain > > briefly what the algorithm is calculating the final percentages > > representing these times. > > They shouldn't need to be massaged. Just sample the values at two > intervals, and your percentages can be calculated by dividing each delta by > the sum of the deltas (since the sum equals the total CPU usage over the > interval, by definition). If you want to calculate per-cpu usage, use the > kern.cp_times sysctl instead.
A bit over a year ago mav@ redesigned powerd's algorithm for measuring 'summary' load for multiple CPUs, as explained with revision 1.21.2.2 at http://www.freebsd.org/cgi/cvsweb.cgi/src/usr.sbin/powerd/powerd.c which code may prove worthwhile exploring, or stealing. cheers, Ian _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[email protected]"
