From: Robert Foss <robert.foss@collabora.com>
To: Michal Hocko <mhocko@kernel.org>, Sonny Rao <sonnyrao@chromium.org>
Cc: 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: Mon, 19 Sep 2016 11:16:31 -0400 [thread overview]
Message-ID: <0769f0c7-7869-2b0f-faac-3b5cbdb6e401@collabora.com> (raw)
In-Reply-To: <20160914091205.GD1612@dhcp22.suse.cz>
On 2016-09-14 05:12 AM, Michal Hocko wrote:
> 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...)
What would this caching look like? Can any information be re-used
between vma walks?
>
> If this would be unacceptable then a new file could be considered.
>
next prev parent reply other threads:[~2016-09-19 15:16 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
2016-09-19 15:16 ` Robert Foss [this message]
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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