Re: [patch 3/4] c/r: procfs: add arg_start/end, env_start/end andexit_code members to /proc/$pid/stat

From: Cyrill Gorcunov
Date: Wed Jan 25 2012 - 02:18:17 EST


On Tue, Jan 24, 2012 at 11:12:45PM -0800, Andrew Morton wrote:
> On Wed, 25 Jan 2012 10:54:50 +0400 Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote:
>
> > > /proc/pid/stat is getting out of control. People are now sending patches
> > > because reading from this thing already takes too long.
>
> err, actually, that was /proc/stat/
>

Ah! (I saw those thread, but then I get confused and thought maybe there were
for /proc/pid/stat as well but I simply missed it ;)

> >
> > I can add prctl PR_GET_MM with subcodes, since PR_SET_MM is already here
> > and wrapped with CHECKPOINT_RESTORE. Would this be better?
>
> mm, not really - /proc is the logical/expected place for it.
>
> I'm thinking that perhaps we should start again with all of this and
> export all this information in brand new, well-designed procfs files.
> We'd still maintain /proc/stat and /proc/pid/stat but people should
> migrate off them. Eventually (10 years?) everyone will be setting their
> CONFIG_PROC_[PID_]STAT to 'n' and perhaps we can retire the things.
>
> Meanwhile, I suppose you may as well continue to make /proc/pid/stat
> even crazier :( It isn't as bad as /proc/stat!
>

At moment indeed it's not that bloated... yet.

> btw, do we really need to do "(mm && permitted)" so many times? ie,
> can we split that seq_printf up and do
>
> if (mm && permitted) {
> seq_printf(m + offset, "%lu", mm->start_data);
> ...
> } else {
> seq_printf(m + offset, "0 0 0 0 0 0 0 0 0");
> }
>
> ? Although this probably won't help much.
>

Yeah we can. I'll update.

Cyrill
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