From: Michal Hocko <mhocko@kernel.org>
To: Sonny Rao <sonnyrao@chromium.org>
Cc: Robert Foss <robert.foss@collabora.com>,
Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>, Hugh Dickins <hughd@google.com>,
Konstantin Khlebnikov <koct9i@gmail.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
John Stultz <john.stultz@linaro.org>,
Minchan Kim <minchan@kernel.org>,
ross.zwisler@linux.intel.com, jmarchan@redhat.com,
Johannes Weiner <hannes@cmpxchg.org>,
Kees Cook <keescook@chromium.org>,
oleg@redhat.com, Al Viro <viro@zeniv.linux.org.uk>,
Mateusz Guzik <mguzik@redhat.com>,
Janis Danisevskis <jdanis@google.com>,
calvinowens@fb.com, Alexey Dobriyan <adobriyan@gmail.com>,
ebiederm@xmission.com, Seth Forshee <seth.forshee@canonical.com>,
Djalal Harouni <tixxdz@gmail.com>,
linux-doc@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ben Zhang <benzh@chromium.org>, Bryan Freed <bfreed@chromium.org>,
Filipe Brandenburger <filbranden@chromium.org>,
Jann Horn <jann@thejh.net>,
linux-api@vger.kernel.org,
Jacek Anaszewski <j.anaszewski@samsung.com>
Subject: Re: [PATCH v5 0/3] mm, proc: Implement /proc/<pid>/totmaps
Date: Wed, 14 Sep 2016 11:12:06 +0200 [thread overview]
Message-ID: <20160914091205.GD1612@dhcp22.suse.cz> (raw)
In-Reply-To: <CAPz6YkXq_QPffYgBJZGxZG9SboTVoCEH2qqCgAuB6YYj1e95ig@mail.gmail.com>
On Tue 13-09-16 13:27:39, Sonny Rao wrote:
> On Tue, Sep 13, 2016 at 12:12 AM, Michal Hocko <mhocko@kernel.org> wrote:
> > On Mon 12-09-16 10:28:53, Sonny Rao wrote:
> >> On Mon, Sep 12, 2016 at 10:15 AM, Michal Hocko <mhocko@kernel.org> 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.
>
> Yes your description of what we want is pretty good. Having a
> reasonable lower bound on the estimate is fine, though we probably
> want to break out swapped out memory separately.
Why would you want to separate that?
> Given that smaps
> doesn't provide this in a straightforward way, what do you think is
> the right way to provide this information?
I would be tempted to sneak it into /proc/<pid>/statm because that looks
like a proper place but getting this information is not for free
performance wise so I am not really sure something that relies on this
file would see unexpected stalls. Maybe this could be worked around by
some caching... I would suggest to check who is actually using this file
(top/ps etc...)
If this would be unacceptable then a new file could be considered.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2016-09-14 9:12 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-05 20:14 [PATCH v5 0/3] mm, proc: Implement /proc/<pid>/totmaps robert.foss
2016-09-05 20:14 ` [PATCH v5 1/3] " robert.foss
2016-09-07 12:58 ` Oleg Nesterov
2016-09-12 22:12 ` Robert Foss
2016-09-05 20:14 ` [PATCH v5 2/3] Documentation/filesystems: Fixed typo robert.foss
2016-09-07 23:22 ` Kees Cook
2016-09-08 0:22 ` Robert Foss
2016-09-08 6:23 ` Jonathan Corbet
2016-09-05 20:14 ` [PATCH v5 3/3] Documentation/filesystems: Added /proc/PID/totmaps documentation robert.foss
2016-09-12 12:02 ` [PATCH v5 0/3] mm, proc: Implement /proc/<pid>/totmaps Michal Hocko
2016-09-12 15:31 ` Sonny Rao
2016-09-12 17:15 ` Michal Hocko
2016-09-12 17:28 ` Sonny Rao
2016-09-13 7:12 ` Michal Hocko
2016-09-13 20:27 ` Sonny Rao
2016-09-14 9:12 ` Michal Hocko [this message]
2016-09-19 15:16 ` Robert Foss
2016-09-19 19:32 ` Michal Hocko
[not found] ` <20160919194001.GE2903@pc.thejh.net>
[not found] ` <20160919195109.GB28639@dhcp22.suse.cz>
2016-09-19 19:56 ` Jann Horn
2016-09-19 20:15 ` Sonny Rao
2016-09-20 0:27 ` Robert Foss
2016-09-20 0:29 ` Sonny Rao
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