From: Michal Hocko <mhocko@kernel.org>
To: Robert Foss <robert.foss@collabora.com>
Cc: Sonny Rao <sonnyrao@chromium.org>,
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>
Subject: Re: [PATCH v5 0/3] mm, proc: Implement /proc/<pid>/totmaps
Date: Mon, 19 Sep 2016 21:32:38 +0200 [thread overview]
Message-ID: <20160919193238.GA28639@dhcp22.suse.cz> (raw)
In-Reply-To: <0769f0c7-7869-2b0f-faac-3b5cbdb6e401@collabora.com>
On Mon 19-09-16 11:16:31, Robert Foss wrote:
> On 2016-09-14 05:12 AM, Michal Hocko wrote:
> > On Tue 13-09-16 13:27:39, Sonny Rao wrote:
[...]
> > > 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?
yes basically return the same value if called within HZ or something
similar. But that assumes that statm latency really matters and it is
called often enough.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2016-09-19 19:32 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
[not found] ` <1473106449-12847-2-git-send-email-robert.foss-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
2016-09-07 12:58 ` Oleg Nesterov
2016-09-12 22:12 ` Robert Foss
[not found] ` <1473106449-12847-1-git-send-email-robert.foss-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
2016-09-05 20:14 ` [PATCH v5 2/3] Documentation/filesystems: Fixed typo robert.foss-ZGY8ohtN/8qB+jHODAdFcQ
2016-09-07 23:22 ` Kees Cook
[not found] ` <CAGXu5jL8w948TMyYPe-O0yoA9GjnWDpdAkFdD91YkechE4Fw-w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
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
[not found] ` <20160912120248.GK14524-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2016-09-12 15:31 ` Sonny Rao
2016-09-12 17:15 ` Michal Hocko
[not found] ` <20160912171503.GB14997-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
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
2016-09-19 19:32 ` Michal Hocko [this message]
[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
[not found] ` <2bfaecf2-bf68-48b2-8a88-6e8997c229db-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
2016-09-20 0:29 ` Sonny Rao
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