[Devel] Re: How to draw values for /proc/stat

[KAMEZAWA Hiroyuki]

On Mon, 5 Dec 2011 07:32:33 -0200
Glauber Costa <glommer at parallels.com> wrote:

> Hi,
> 
> Specially Peter and Paul, but all the others:
> 
> As you can see in https://lkml.org/lkml/2011/12/4/178, and in my answer 
> to that, there is a question - one I've asked before but without that 
> much of an audience - of whether /proc files read from process living on 
> cgroups should display global or per-cgroup resources.
> 
> In the past, I was arguing for a knob to control that, but I recently 
> started to believe that a knob here will only overcomplicate matters:
> if you live in a cgroup, you should display only the resources you can 
> possibly use. Global is for whoever is in the main cgroup.
> 

Hm. I have a suggestion and a concern.

(A suggestion)
   How about having a mount option for procfs ?
   For example,
	mount -t proc .... -o cgroup_virtualized
   Then, /proc/stat etc shows per-cgroup information.

(A concern)
   /proc/stat will be a mixture of virtualized values and not-virtualized values.
   1. Don't users need to know whether each value is virtualized or not ?
   2. Can we have a way to show "this value is virtualized!" annotation ?


> Now, it comes two questions:
> 1) Do you agree with that, for files like /proc/stat ? I think the most 
> important part is to be consistent inside the system, regardless of what 
> is done
> 
I think some kind of care for users are required as I wrote above.


> 2) Will cpuacct stay? I think if it does, that becomes almost mandatory 
> (at least the bind mount idea is pretty much over here), because drawing 
> value for /proc/stat becomes quite complex.
> The cpuacct cgroup can provide user, sys, etc values. But we also have:
> 

If virtualized /proc/stat works, I don't think 'account only' cgroup is
necessary. It can be obsolete.

Thanks,
-Kame