[collectd] Monitor CPU usage for a specific process

[Bruno Prémont]

On Sat, 22 Aug 2015 21:36:48 "Zhou, Zhenyu" wrote:
> Thanks a lot! I'm trying to figure out how to set CGroup now - don't
> know it before.
> 
> One more question, I just find /proc/[PID]/stat also contains such
> information:
> processCPUTime = utime + stime + cutime + cstime
> 
> I'm wondering whether there are any significant differences from
> reading /proc directly and the way Collectd used?

Collectd is reading from /proc files. So if the processes plugin does
monitor the appropriate stats, then it is reading exactly those files.

In the case of cgroups, the files being read are located on the cgroups
filesystem (usually somewhere below /sys/fs/cgroup/).


So collectd is just automating the data collection for you. Have a look
at the sources to determine where the individual data points are
obtained from.
Local kernel-originated stats are mostly read from /proc, /sys or over
netlink.

Bruno

> Thank you!
> 
> Zhenyu
> 
> At2015-08-22 20:32:29,Zhou, Zhenyu<zzyzzy at pku.org.cn>wrote:
> > Hello,
> > 
> > On Sat, 22 Aug 2015 20:10:25 "Zhou, Zhenyu" wrote:
> > > I'm new to Collectd and would like to use it to measure CPU utilization.
> > > However, after starting the daemon and collecting results, I do not
> > > find CPU utilization for a single process among the .rrd files. I only
> > > find the data for overall system.
> > > 
> > > Does anyone have idea how to measure it for one process (according to
> > > its PID)? Or does Collectd support such functionality?
> > 
> > The CPU plugin can only monitor per-CPU usage (and eventually a system
> > average).
> > 
> > To monitor per-process usage you might be able to use process plugin
> > (not sure) or cgroups (place the process you want to monitor in its own
> > cgroup for CPU accounting and use cgroup plugin).
> > 
> > Bruno
>