From: Sonny Rao <sonnyrao@chromium.org>
To: Robert Foss <robert.foss@collabora.com>
Cc: Michal Hocko <mhocko@kernel.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 17:29:56 -0700 [thread overview]
Message-ID: <CAPz6YkWWUJLPauKZ6yQuVfZY0etNM+LSU4Z0TW+Lj8xHPnkcuQ@mail.gmail.com> (raw)
In-Reply-To: <2bfaecf2-bf68-48b2-8a88-6e8997c229db@collabora.com>
On Mon, Sep 19, 2016 at 5:27 PM, Robert Foss <robert.foss@collabora.com> wrote:
>
>
> 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?
It's a single application -- and it definitely doesn't query at HZ --
especially given how long it takes to gather the data :-)
prev parent reply other threads:[~2016-09-20 0:37 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
2016-09-20 0:29 ` Sonny Rao [this message]
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