From: Sonny Rao <sonnyrao@chromium.org> To: Michal Hocko <mhocko@kernel.org> Cc: Robert Foss <robert.foss@collabora.com>, 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@canonical.com, 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, 12 Sep 2016 08:31:36 -0700 [thread overview] Message-ID: <CAPz6YkVRcCkwv7WvdTQMH-UHhLK_k51QtNNOmNw7ySk7pfgD8w@mail.gmail.com> (raw) In-Reply-To: <20160912120248.GK14524@dhcp22.suse.cz> On Mon, Sep 12, 2016 at 5:02 AM, Michal Hocko <mhocko@kernel.org> wrote: > On Mon 05-09-16 16:14:06, robert.foss@collabora.com wrote: >> From: Robert Foss <robert.foss@collabora.com> >> >> This series provides the /proc/PID/totmaps feature, which >> summarizes the information provided by /proc/PID/smaps for >> improved performance and usability reasons. >> >> A use case is to speed up monitoring of memory consumption in >> environments where RSS isn't precise. >> >> For example Chrome tends to many processes which have hundreds of VMAs >> with a substantial amount of shared memory, and the error of using >> RSS rather than PSS tends to be very large when looking at overall >> memory consumption. PSS isn't kept as a single number that's exported >> like RSS, so to calculate PSS means having to parse a very large smaps >> file. >> >> This process is slow and has to be repeated for many processes, and we >> found that the just act of doing the parsing was taking up a >> significant amount of CPU time, so this patch is an attempt to make >> that process cheaper. > > I still maintain my concerns about a single pss value. It might work in > a very specific situations where the consumer knows what is shared but > other than that the value can be more misleading than helpful. So a NACK > from me until I am shown that this is usable in general and still > helpful. I know you think Pss isn't useful in general (though I'll point out two other independent people said they found it useful) but how about the other fields like Swap, Private_Dirty and Private_Shared? If we removed Pss would you still NACK it? > > -- > Michal Hocko > SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Sonny Rao <sonnyrao-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> To: Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Cc: Robert Foss <robert.foss-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>, Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Vlastimil Babka <vbabka-AlSwsSmVLrQ@public.gmane.org>, Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Konstantin Khlebnikov <koct9i-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Naoya Horiguchi <n-horiguchi-PaJj6Psr51x8UrSeD/g0lQ@public.gmane.org>, "Kirill A. Shutemov" <kirill.shutemov-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>, John Stultz <john.stultz-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Minchan Kim <minchan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, jmarchan-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>, Mateusz Guzik <mguzik-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Janis Danisevskis <jdanis-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, calvinowens-b10kYP2dOMg@public.gmane.org, Alexey Dobriyan <adobriyan-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org, seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org, tixxdz@g Subject: Re: [PATCH v5 0/3] mm, proc: Implement /proc/<pid>/totmaps Date: Mon, 12 Sep 2016 08:31:36 -0700 [thread overview] Message-ID: <CAPz6YkVRcCkwv7WvdTQMH-UHhLK_k51QtNNOmNw7ySk7pfgD8w@mail.gmail.com> (raw) In-Reply-To: <20160912120248.GK14524-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org> On Mon, Sep 12, 2016 at 5:02 AM, Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote: > On Mon 05-09-16 16:14:06, robert.foss-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org wrote: >> From: Robert Foss <robert.foss-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org> >> >> This series provides the /proc/PID/totmaps feature, which >> summarizes the information provided by /proc/PID/smaps for >> improved performance and usability reasons. >> >> A use case is to speed up monitoring of memory consumption in >> environments where RSS isn't precise. >> >> For example Chrome tends to many processes which have hundreds of VMAs >> with a substantial amount of shared memory, and the error of using >> RSS rather than PSS tends to be very large when looking at overall >> memory consumption. PSS isn't kept as a single number that's exported >> like RSS, so to calculate PSS means having to parse a very large smaps >> file. >> >> This process is slow and has to be repeated for many processes, and we >> found that the just act of doing the parsing was taking up a >> significant amount of CPU time, so this patch is an attempt to make >> that process cheaper. > > I still maintain my concerns about a single pss value. It might work in > a very specific situations where the consumer knows what is shared but > other than that the value can be more misleading than helpful. So a NACK > from me until I am shown that this is usable in general and still > helpful. I know you think Pss isn't useful in general (though I'll point out two other independent people said they found it useful) but how about the other fields like Swap, Private_Dirty and Private_Shared? If we removed Pss would you still NACK it? > > -- > Michal Hocko > SUSE Labs
next prev parent reply other threads:[~2016-09-12 15:41 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 [this message] 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 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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