From: jacob pan <jacob.jun.pan@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
Paul Menage <menage@google.com>, Li Zefan <lizf@cn.fujitsu.com>,
Thomas Gleixner <tglx@linutronix.de>,
containers@lists.linux-foundation.org,
Arjan van de Ven <arjan@linux.intel.com>,
linux-kernel@vger.kernel.org, Matt Helsley <matthltc@us.ibm.com>,
linux-api@vger.kernel.org
Subject: Re: [PATCH, v9 3/3] cgroups: introduce timer slack controller
Date: Wed, 16 Mar 2011 04:35:45 -0700 [thread overview]
Message-ID: <20110316043545.493c7b36@jacob-laptop> (raw)
In-Reply-To: <20110314164652.5b44fb9e.akpm@linux-foundation.org>
On Mon, 14 Mar 2011 16:46:52 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:
> On Mon, 14 Mar 2011 16:05:24 +0200
> Kirill A. Shutemov" <kirill@shutemov.name> wrote:
>
> > +Overview
> > +--------
> > +
> > +Every task_struct has timer_slack_ns value. This value uses to
> > round up +poll() and select() timeout values. This feature can be
> > useful in +mobile environment where combined wakeups are desired.
> > +
> > +Originally, prctl() was the only way to change timer slack value of
> > +a process. So you was not able change timer slack value of another
> > +process.
> > +
> > +cgroup subsys "timer_slack" implements timer slack controller. It
> > +provides a way to set minimal timer slack value for a group of
> > tasks. +If a task belongs to a cgroup with minimal timer slack
> > value higher than +task's value, cgroup's value will be applied.
> > +
> > +Timer slack controller allows to implement setting timer slack
> > value of +a process based on a policy. For example, you can create
> > foreground and +background cgroups and move tasks between them
> > based on system state.
>
> (quoting myself from last time)
>
> Why do we need a cgroup for this as opposed to (say) inheritance over
> fork(), or a system-wide knob, or a per-process/threadgroup knob, or
> just leaving the existing code as-is? Presumably you felt that a
> cgroup approach is better for manageability, but you didn't tell us
> about this and you didn't explore alternative ways of solving the
> problem-which-you-didn't-describe.
>
>
>
>
> I'm still having trouble seeing why we should merge this. Who will
> use it, and for what reason and what benefits will they see?
> Quantified benefits, if possible!
>
I am planning to use it for doing resource management for a mobile
device where we classify applications by groups based on priority and
trust level. Then at runtime, I plan to use timer slack as one of the
knobs to penalize/manage them at different degree to reduce power
consumption (via reduction of #wake-ups in this case).
Thanks,
Jacob
prev parent reply other threads:[~2011-03-16 11:35 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-14 14:05 [PATCH, v9 0/3] Introduce timer slack controller Kirill A. Shutemov
2011-03-14 14:05 ` [PATCH, v9 1/3] hrtimer: introduce effective timer slack Kirill A. Shutemov
2011-03-14 14:05 ` [PATCH, v9 2/3] hrtimer: implement PR_GET_EFFECTIVE_TIMERSLACK Kirill A. Shutemov
2011-03-14 14:05 ` [PATCH, v9 3/3] cgroups: introduce timer slack controller Kirill A. Shutemov
2011-03-14 23:46 ` Andrew Morton
2011-03-15 9:11 ` Kirill A. Shutemov
2011-03-16 11:35 ` jacob pan [this message]
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