[Devel] Re: [PATCH] Cpu statistics accounting based on Paul Menage patches

[Balbir Singh]

Andrew Morton wrote:
> On Wed, 11 Apr 2007 19:02:27 +0400
> Pavel Emelianov <xemul at sw.ru> wrote:
> 
>> Provides a per-container statistics concerning the numbers of tasks
>> in various states, system and user times, etc. Patch is inspired
>> by Paul's example of the used CPU time accounting. Although this
>> patch is independent from Paul's example to make it possible playing
>> with them separately.
> 
> Why is this actually needed?  If userspace has a list of the tasks which
> are in a particular container, it can run around and add up the stats for
> those tasks without kernel changes?
> 
> It's a bit irksome that we have so much accounting of this form in core
> kernel, yet we have to go and add a completely new implementation to create
> something which is similar to what we already have.  But I don't
> immediately see a fix for that.  Apart from paragraph #1 ;)
> 
> Should there be linkage between per-container stats and
> delivery-via-taskstats?  I can't think of one, really.
> 
> You have cpu stats.  Later, presumably, we'll need IO stats, MM stats,
> context-switch stats, number-of-syscall stats, etc, etc.  Are we going to
> reimplement all of those things as well?  See paragraph #1!
> 
> Bottom line: I think we seriously need to find some way of consolidating
> per-container stats with our present per-task stats.  Perhaps we should
> instead be looking at ways in which we can speed up paragraph #1.


This should be easy to build. per container stats can live in parallel
with per-task stats, but they can use the same general mechanism for
data communication to user space.

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL