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. >
WARNING: multiple messages have this Message-ID (diff)
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> 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: 43+ 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 ` robert.foss 2016-09-05 20:14 ` [PATCH v5 1/3] " robert.foss 2016-09-05 20:14 ` robert.foss 2016-09-07 12:58 ` Oleg Nesterov 2016-09-07 12:58 ` Oleg Nesterov 2016-09-12 22:12 ` Robert Foss 2016-09-12 22:12 ` Robert Foss 2016-09-05 20:14 ` [PATCH v5 2/3] Documentation/filesystems: Fixed typo robert.foss 2016-09-05 20:14 ` robert.foss-ZGY8ohtN/8qB+jHODAdFcQ 2016-09-07 23:22 ` Kees Cook 2016-09-07 23:22 ` Kees Cook 2016-09-08 0:22 ` Robert Foss 2016-09-08 0:22 ` Robert Foss 2016-09-08 6:23 ` Jonathan Corbet 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 2016-09-05 20:14 ` 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 15:31 ` Sonny Rao 2016-09-12 17:15 ` Michal Hocko 2016-09-12 17:15 ` Michal Hocko 2016-09-12 17:28 ` Sonny Rao 2016-09-12 17:28 ` Sonny Rao 2016-09-13 7:12 ` Michal Hocko 2016-09-13 7:12 ` Michal Hocko 2016-09-13 20:27 ` Sonny Rao 2016-09-13 20:27 ` Sonny Rao 2016-09-14 9:12 ` Michal Hocko 2016-09-14 9:12 ` Michal Hocko 2016-09-19 15:16 ` Robert Foss [this message] 2016-09-19 15:16 ` Robert Foss 2016-09-19 19:32 ` Michal Hocko 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 19:56 ` Jann Horn 2016-09-19 20:15 ` Sonny Rao 2016-09-19 20:15 ` Sonny Rao 2016-09-20 0:27 ` Robert Foss 2016-09-20 0:27 ` Robert Foss 2016-09-20 0:29 ` Sonny Rao 2016-09-20 0:29 ` Sonny Rao
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