Re: [PATCH 3/7] proc: Introduce the Children: line in /proc/<pid>/status

[Pavel Emelyanov <xemul-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>]

On 07/23/2011 12:41 PM, Tejun Heo wrote:
> Hello,
> 
> On Sat, Jul 23, 2011 at 12:06:46PM +0400, Pavel Emelyanov wrote:
>>> The dumper would have to build full process tree anyway so I don't 
>>> see much point in providing backlink from kernel.
>>
>> Hm... Why would a dumper need to build the whole tree? Maybe you're
>> right with this, so can you elaborate?
> 
> It depends on what you want to dump.  Dumping arbitrary task has
> issues even at the most basic level due to relationships among family
> of processes, which I assume is why the in-kernel CR was primarily
> focused on dumping and restoring full namespaces.  If you're doing
> that, there is no avoiding walking process tree anyway (which
> apparently can even be per-NS using uprocfs).

OK I see. Then my answer is - typically a container looks like an init task
with everybody else growing from that point. Having a machine with 1000 of
containers building the whole /proc tree in memory to dump a single container
would be MUCH more expensive that having this small like in proc.

> Thanks.
>