Re: [rfc 2/3] fs, proc: Introduce the Children: line in /proc/<pid>/status

[Pavel Emelyanov <xemul@parallels.com>]

On 12/02/2011 04:41 PM, Pedro Alves wrote:
> On Friday 02 December 2011 00:40:10, KAMEZAWA Hiroyuki wrote:
>>> What about this one?
>>> ---
>>> fs, proc: Introduce the /proc/<pid>/children entry
>>>
>>> There is no easy way to make a reverse parent->children chain
>>> from the task status, in turn children->parent provided with "PPid"
>>> field.
>>>
>>> So instead of walking over all pids in system to figure out what
>>> children the task have -- we add explicit /proc/<pid>/children entry,
>>> since kernel already knows this kind of information but it was not
>>> yet exported.
>>>
>>> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
>>> Cc: Pavel Emelyanov <xemul@parallels.com>
>>> Cc: Serge Hallyn <serge.hallyn@canonical.com>
>>> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>>
>> Yes, I like /children file. other points seems to be pointed out by other
>> reviewers. 
> 
> Any reason this is a file instead of a directory like /proc/PID/task/ ?
> 
> $ sudo ls /proc/8167/task/
> 8167  854  855  856  857  858  859
> $ sudo ls /proc/8167/task/855/
> attr    clear_refs  cpuset   exe     io       loginuid  mountinfo  oom_adj        pagemap      sched      smaps  statm    wchan
> auxv    cmdline     cwd      fd      latency  maps      mounts     oom_score      personality  schedstat  stack  status
> cgroup  comm        environ  fdinfo  limits   mem       numa_maps  oom_score_adj  root         sessionid  stat   syscall
> 
> Much easier to follow the chain from the command line this way.

What do you propose to put into these directories? Another directories named with
children pid-s?