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Message-ID: <20100104001516.GE16187@balbir.in.ibm.com>
Date: Mon, 4 Jan 2010 05:45:16 +0530
From: Balbir Singh <balbir@...ux.vnet.ibm.com>
To: "Kirill A. Shutemov" <kirill@...temov.name>
Cc: containers@...ts.linux-foundation.org, linux-mm@...ck.org,
Paul Menage <menage@...gle.com>,
Li Zefan <lizf@...fujitsu.com>,
Andrew Morton <akpm@...ux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Pavel Emelyanov <xemul@...nvz.org>,
Dan Malek <dan@...eddedalley.com>,
Vladislav Buzov <vbuzov@...eddedalley.com>,
Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
Alexander Shishkin <virtuoso@...nd.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/4] cgroup notifications API and memory thresholds
* Kirill A. Shutemov <kirill@...temov.name> [2009-12-27 20:37:57]:
> On Sun, Dec 27, 2009 at 2:47 PM, Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> > * Kirill A. Shutemov <kirill@...temov.name> [2009-12-27 04:08:58]:
> >
> >> This patchset introduces eventfd-based API for notifications in cgroups and
> >> implements memory notifications on top of it.
> >>
> >> It uses statistics in memory controler to track memory usage.
> >>
> >> Output of time(1) on building kernel on tmpfs:
> >>
> >> Root cgroup before changes:
> >> make -j2 506.37 user 60.93s system 193% cpu 4:52.77 total
> >> Non-root cgroup before changes:
> >> make -j2 507.14 user 62.66s system 193% cpu 4:54.74 total
> >> Root cgroup after changes (0 thresholds):
> >> make -j2 507.13 user 62.20s system 193% cpu 4:53.55 total
> >> Non-root cgroup after changes (0 thresholds):
> >> make -j2 507.70 user 64.20s system 193% cpu 4:55.70 total
> >> Root cgroup after changes (1 thresholds, never crossed):
> >> make -j2 506.97 user 62.20s system 193% cpu 4:53.90 total
> >> Non-root cgroup after changes (1 thresholds, never crossed):
> >> make -j2 507.55 user 64.08s system 193% cpu 4:55.63 total
> >>
> >> Any comments?
> >
> > Thanks for adding the documentation, now on to more critical questions
> >
> > 1. Any reasons for not using cgroupstats?
>
> Could you explain the idea? I don't see how cgroupstats applicable for
> the task.
cgroupstats allows you to notify task statistics or send
notifications, hence the applicability.
>
> > 2. Is there a user space test application to test this code.
>
> Attached. It's not very clean, but good enough for testing propose.
> Example of usage:
>
> $ echo '/cgroups/memory.usage_in_bytes 1G' | ./cgroup_event_monitor
>
Thanks, I'll test it right now.
> > IIUC,
> > I need to write a program that uses eventfd(2) and then passes
> > the eventfd descriptor and thresold to cgroup.*event* file and
> > then the program will get notified when the threshold is reached?
>
> You need to pass eventfd descriptor, descriptor of control file to be
> monitored (memory.usage_in_bytes or memory.memsw.usage_in_bytes) and
> threshold.
>
> Do you want to rename cgroup.event_control to cgroup.event?
No, event_control seems like a good name ATM.
--
Balbir
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