From: Robert Foss <robert.foss@collabora.com>
To: Michal Hocko <mhocko@kernel.org>
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>,
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 20:27:23 -0400 [thread overview]
Message-ID: <2bfaecf2-bf68-48b2-8a88-6e8997c229db@collabora.com> (raw)
In-Reply-To: <20160919193238.GA28639@dhcp22.suse.cz>
On 2016-09-19 03:32 PM, Michal Hocko wrote:
> 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.
Any single application querying more often than HZ, would presumably do
so for accuracy reasons.
However for multiple applications that combined query more often than
HZ, this would most definitely be halpful in terms of performance.
@Sonny, does chromiumos fall into the first or second category?
next prev parent reply other threads:[~2016-09-20 0:27 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
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 [this message]
2016-09-20 0:29 ` Sonny Rao
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