Re: [Xenomai-core] [RFC, PATCH] per-thread exec-time stats

[Philippe Gerum <rpm@xenomai.org>]

On Fri, 2006-07-07 at 11:03 +0200, Jan Kiszka wrote:
> >> Far too complex in my eyes for this simple purpose (what's the pid of
> >> kernel-only threads?) -
> > 
> > It's symbolic name. It's not a matter of simplicity, your patch for that
> > purpose is rather complex already.
> 
> Haven't measured, but the amount of code added for collecting the data
> and printing just another column should be marginal as yet. Introducing
> a new infrastructure for more /proc subdirs with probably multiple
> entries would certainly cost more.
> 

This has no cost on the real-time side of things. In contrast, scanning
the threadq within /proc handlers like /stats and /sched are doing now,
does have some noticeable cost. By having separate per-thread entries,
we provide the necessary infrastructure for exporting more raw
statistical data to user-space tools, in a format which would be
script-friendly.

> > 
> >>  and we need to solve the latency problem of
> >> /sched and /stat anyway.
> > 
> > That's separate issues. Solving the scalability issue
> > of /proc/xenomai/stats and friends does not improve their usability in
> > the context of user-space tools monitoring thread activity. E.g. how are
> > we going to extend the reporting about such activity if need be, adding
> > yet another column to /stats and /sched?
> 
> As long as there are no stand-alone tools relying on the layout, just
> only our own ones - fairly simple. But before speculating more, I will
> have a look now how simple such tool/script may actually be.
> 
> Jan
> 
-- 
Philippe.