Re: [PATCH v5 0/3] mm, proc: Implement /proc/<pid>/totmaps

[Michal Hocko]

On Mon 12-09-16 10:28:53, Sonny Rao wrote:
> On Mon, Sep 12, 2016 at 10:15 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> > On Mon 12-09-16 08:31:36, Sonny Rao wrote:
[...]
> >> but how about the other fields like Swap, Private_Dirty and
> >> Private_Shared?
> >
> > Private_Shared can be pretty confusing as well without the whole context
> > as well see my other emails in the original thread (just to remind
> > shmem/tmpfs makes all this really confusing).
> 
> But this is exactly the issue -- RSS is can be just as confusing if
> you don't know something about the application.

I agree that rss can be confusing but we will not make the situation any
better if we add yet another confusing metric.

> I think the issue is
> how common that situation is, and you seem to believe that it's so
> uncommon that it's actually better to keep the information more
> difficult to get for those of us who know something about our systems.
> 
> That's fine, I guess we just have to disagree here, thanks for look at this.

I think you should just step back and think more about what exactly
you expect from the counter(s). I believe what you want is an
estimate of a freeable memory when the particular process dies or is
killed. That would mean resident single mapped private anonymous memory
+ unlinked single mapped shareable mappings + single mapped swapped out
memory. Maybe I've missed something but it should be something along
those lines. Definitely something that the current smaps infrastructure
doesn't give you, though.
-- 
Michal Hocko
SUSE Labs