Peter Tribble wrote:
Looking at the recent zonestat arc case reminded me of something
I've been meaning to ask for a while.

In the case, it says:

prstat polls /proc, and will not account for
cpu used by short-lived processes.


Extended accounting must be used to
compute the cpu utilization because it will contain all data
associated with processes which have exited.

And this is something that's been discussed before.

Now, if you want to account for cpu utilization by children,
why not use the pr_ctime member of the psinfo structure?
As far as I understand it, that collects cpu for child processes
that exit, so why can't that be used instead of monkeying
about with extended accounting?

What am I overlooking here?

I haven't explored an algorithm for tracking that. At some point, the child is running, in which case I may have added its current usage to the zone's usage. When the children exit later, I would need to figure out the parent the usage was added to so I can avoid double counting usage I've already charged to the zone.

The other bit to solve would be zone-entered processes, which will have a parent in the global zone. The usage by the"in-the-zone" children would bubble up to a parent in the global zone. This would certainly be wrong.


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