From: Peter Zijlstra <peterz@infradead.org>
To: Raistlin <raistlin@linux.it>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
Chris Friesen <cfriesen@nortel.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Darren Hart <darren@dvhart.com>, Henrik Austad <henrik@austad.us>,
Johan Eker <johan.eker@ericsson.com>,
"p.faure" <p.faure@akatech.ch>,
linux-kernel <linux-kernel@vger.kernel.org>,
Claudio Scordino <claudio@evidence.eu.com>,
michael trimarchi <trimarchi@retis.sssup.it>,
Fabio Checconi <fabio@gandalf.sssup.it>,
Tommaso Cucinotta <t.cucinotta@sssup.it>,
Juri Lelli <juri.lelli@gmail.com>,
Nicola Manica <nicola.manica@gmail.com>,
Luca Abeni <luca.abeni@unitn.it>
Subject: Re: [RFC][PATCH 09/11] sched: first draft of deadline inheritance.
Date: Wed, 14 Apr 2010 10:25:00 +0200 [thread overview]
Message-ID: <1271233500.32749.10.camel@laptop> (raw)
In-Reply-To: <1267385165.13676.99.camel@Palantir>
On Sun, 2010-02-28 at 20:26 +0100, Raistlin wrote:
> Therefore, as of now, this patch:
> - implements priority inheritance for -deadline tasks, according to
> what described above;
> - to make this possible without rewriting outstanding chunks of
> code of both -deadline scheduling and existing PI, the task's
> relative deadline is stored in the prio field of the task_struct.
> This is done in such a way that:
> * prio is always < 0 for -deadline tasks,
> * p1->prio < p2->prio still means p1 has higher priority than
> p2, i.e., in our case, p1 has smaller relative deadline.
> - the point above means that, since prio is of int type, a relative
> deadline has to be smaller than INT_MAX. This is about 2sec,
> which is a something (we think! :-)) we can afford, at least
> for now.
Right, except that this makes the plist stuff O(INT_MAX) [ or rather
O(nr_dl_tasks) ].
But I guess it serves for testing.
I think it would be relatively straight forward to modify the existing
PI chain code to work using an RB-tree instead of the plist stuff.
An RB-tree would also make the whole ->prio mess much easier to solve,
we could simply make a more complex comparison function, like:
int rt_mutex_prio_less(struct task_struct *left, struct task_struct *right)
{
if (left->prio < right->prio)
return 1;
if (left->prio == right->prio && left->prio == -1) {
if (left->deadline < right->deadline)
return 1;
}
return 0;
}
Which uses the static prio -1 to represent all deadline tasks.
> - disables bandwidth throttling for tasks while they are deadline
> boosted. It also tries to make them pay back for runtime overrun
> and deadline misses in this phase, but it's only "local", in the
> sense that instances farther than the one right next to the
> overrun are not going to be direcly affected.
>
Yeah, good enough to start with ;-)
next prev parent reply other threads:[~2010-04-15 7:29 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-28 19:06 [RFC][PATCH 0/11] sched: SCHED_DEADLINE v2 Raistlin
2010-02-28 19:15 ` [RFC][PATCH 01/11] sched: add sched_class->task_dead Raistlin
2010-02-28 19:17 ` [RFC][PATCH 02/11] sched: SCHED_DEADLINE policy implementation Raistlin
2010-04-13 18:22 ` Peter Zijlstra
2010-04-13 18:22 ` Peter Zijlstra
2010-04-13 18:22 ` Peter Zijlstra
2010-04-13 18:55 ` Steven Rostedt
2010-04-15 7:34 ` Peter Zijlstra
2010-04-13 18:22 ` Peter Zijlstra
2010-04-13 18:22 ` Peter Zijlstra
2010-02-28 19:18 ` [RFC][PATCH 03/11] sched: add extended scheduling interface Raistlin
2010-02-28 19:19 ` [RFC][PATCH 04/11] sched: add resource limits for -deadline tasks Raistlin
2010-02-28 19:20 ` [RFC][PATCH 05/11] sched: add a syscall to wait for the next instance Raistlin
2010-02-28 19:22 ` [RFC][PATCH 06/11] sched: add the sched-debug bits for sched_dl Raistlin
2010-02-28 19:23 ` [RFC][PATCH 07/11] sched: add latency tracing for -deadline tasks Raistlin
2010-02-28 19:24 ` [RFC][PATCH 08/11] sched: send SIGXCPU at -deadline task overruns Raistlin
2010-04-13 18:22 ` Peter Zijlstra
2010-04-13 19:32 ` Oleg Nesterov
2010-02-28 19:26 ` [RFC][PATCH 09/11] sched: first draft of deadline inheritance Raistlin
2010-04-14 8:25 ` Peter Zijlstra [this message]
2010-04-14 9:45 ` Peter Zijlstra
2010-02-28 19:27 ` [RFC][PATCH 10/11] sched: add bandwidth management for sched_dl Raistlin
2010-04-14 10:09 ` Peter Zijlstra
2010-02-28 19:28 ` [RFC][PATCH 11/11] sched: add sched_dl documentation Raistlin
2010-04-14 10:17 ` [RFC][PATCH 0/11] sched: SCHED_DEADLINE v2 Peter Zijlstra
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