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From: Peter Zijlstra <peterz@infradead.org>
To: Fabio Checconi <fchecconi@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
	Paul Turner <pjt@google.com>,
	Dario Faggioli <faggioli@gandalf.sssup.it>,
	Michael Trimarchi <michael@evidence.eu.com>,
	Dhaval Giani <dhaval@retis.sssup.it>,
	Tommaso Cucinotta <t.cucinotta@sssup.it>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/3] sched: use EDF to throttle RT task groups v2
Date: Thu, 25 Feb 2010 21:28:16 +0100	[thread overview]
Message-ID: <1267129696.22519.556.camel@laptop> (raw)
In-Reply-To: <cover.1266931410.git.fabio@helm.retis>

On Tue, 2010-02-23 at 19:56 +0100, Fabio Checconi wrote:
> This patchset introduces a group level EDF scheduler extending the
> throttling mechanism, in order to make it support generic period
> assignments.  With this patch, the runtime and period parameters
> can be used to specify arbitrary CPU reservations for RT tasks.
> 
> From the previous post [1] I've integrated Peter's suggestions, using
> a multi-level hierarchy to do admission control, but a one-level only
> equivalent hierarchy for scheduling, and I've not removed the bandwidth
> migration mechanism, trying to adapt it to EDF scheduling.  In this
> version tasks are still inserted into priority arrays and only groups
> are kept in a per-rq edf tree.
> 
> The main design issues involved:
> 
>   - Since it is not easy to mix tasks and groups on the same scheduler
>     queue (tasks have no deadlines), the bandwidth reserved to the tasks
>     in a group is controlled with two additional cgroup attributes:
>     rt_task_runtime_us and rt_task_period_us.  These attributes control,
>     within a cgroup, how much bandwidth is reserved to the tasks it
>     contains.  The old attributes, rt_runtime_us and rt_period_us, are
>     still there, and control the bandwidth assigned to the cgroup.  They
>     are used only for admission control.
> 
>   - Shared resources are still handled using boosting.  When a group
>     contains a task inside a critical section it is scheduled according
>     the highest priority among the ones of the tasks it contains.
>     In this way, the same group has two modes: when it is not boosted
>     it is scheduled according to its deadline; when it is boosted, it
>     is scheduled according its priority.  Boosted groups are always
>     favored over non-boosted ones.
> 
>   - Given that the various rt_rq's belonging to the same task group
>     are activated independently, there is the need of a timer per
>     each rt_rq.
> 
>   - While balancing the bandwidth assigned to a cgroup on various cpus
>     we have to make sure that utilization for the rt_rq's on each cpu
>     does not exceed the global utilization limit for RT tasks.  
> 

> As usual, feedback welcome.

Looks very nice, good work! comments in individual replies.


  parent reply	other threads:[~2010-02-25 21:43 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-02-23 18:56 Fabio Checconi
2010-02-23 18:56 ` [PATCH 1/3] sched: use EDF to schedule groups Fabio Checconi
2010-02-25 20:28   ` Peter Zijlstra
2010-03-03 16:59     ` Fabio Checconi
2010-02-23 18:56 ` [PATCH 2/3] sched: enforce per-cpu utilization limits on runtime balancing Fabio Checconi
2010-02-25 20:28   ` Peter Zijlstra
2010-03-03 16:59     ` Fabio Checconi
2010-02-25 20:28   ` Peter Zijlstra
2010-03-03 17:00     ` Fabio Checconi
2010-03-23 20:32       ` Peter Zijlstra
2010-02-25 20:28   ` Peter Zijlstra
2010-03-03 16:59     ` Fabio Checconi
2010-02-25 20:28   ` Peter Zijlstra
2010-03-03 17:00     ` Fabio Checconi
2010-03-23 20:33       ` Peter Zijlstra
2010-02-25 20:28   ` Peter Zijlstra
2010-03-03 17:00     ` Fabio Checconi
2010-02-23 18:56 ` [PATCH 3/3] sched: make runtime balancing code more EDF-friendly Fabio Checconi
2010-02-25 20:28   ` Peter Zijlstra
2010-03-03 17:01     ` Fabio Checconi
2010-02-25 20:28 ` Peter Zijlstra [this message]
2010-02-27 12:33 ` [PATCH 0/3] sched: use EDF to throttle RT task groups v2 Peter Zijlstra
2010-03-03 17:01   ` Fabio Checconi
2010-03-23 20:30     ` Peter Zijlstra
2010-03-23 20:56       ` Dhaval Giani
2010-03-23 21:51         ` Tommaso Cucinotta

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