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

From: Pedro Alves
Date: Fri Dec 02 2011 - 07:41:19 EST


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@xxxxxxxxxx>
> > Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
> > Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
> > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>
> 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
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