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

[Pedro Alves <pedro@codesourcery.com>]

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.

-- 
Pedro Alves