G'Day,
On Tue, Oct 09, 2007 at 03:15:40AM -0700, J.J. Shore wrote:
> The tool DTraceToolKit-0.99/Kernal/cputimes under reads the IDLE time when
> some of the CPUs are completely idle for long periods.
>
> I have an 8 CPU box which is not doing much. If I run cputimes on it for an
> interval of 5 seconds and add up the times then the sum only comes to about
> 50%
> of the available time. I understand that this is because the probes,
> sysinfo:unix:idle_enter:idlethread
> sched:::on-cpu and
> sched:::remain-cpu
> will not fire for any given CPU until it has been busy. cputimes relies on
> one
> of these probes firing to start the counting for each CPU. If a CPU is totally
> idle it will not be counted by cputimes.
Yes (although I've never seen this on my development environment as I have
either single or two CPU servers only). I can fix this, but it would require
either an fbt probe (making the script unstable) or destructive tomfoolery.
I'll at least note this in the docs, thanks.
It might help if cputimes printed the number of seen CPUs during each
interval, eg,
# ./cputimes 1 3
2005 Apr 27 23:37:58, traced CPUs: 7/8
THREADS TIME (ns)
KERNEL 10795499
PROCESS 20941091
IDLE 970707443
Brendan
--
Brendan
[CA, USA]
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