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From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	linux-kernel@vger.kernel.org,
	Luca Abeni <luca.abeni@santannapisa.it>,
	Tommaso Cucinotta <tommaso.cucinotta@santannapisa.it>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vineeth Pillai <vineeth@bitbyteword.org>,
	Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [RFC PATCH V3 6/6] sched/fair: Implement starvation monitor
Date: Mon, 19 Jun 2023 14:02:15 +0200	[thread overview]
Message-ID: <20230619120215.GO38236@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230616120507.GM83892@hirez.programming.kicks-ass.net>

On Fri, Jun 16, 2023 at 02:05:07PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 13, 2023 at 03:41:30PM +0200, Daniel Bristot de Oliveira wrote:
> 
> > In an 0-laxity scheduler, the server would run at 0-laxity, jumping in
> > front of DL tasks... that would break EDF. It would be mixing two
> > schedulers in one. It is not required and likely not a good idea either.
> 
> I did consider a hybrid 0-laxity and EDF scheduler for mixed
> criticality, as have others like Ted Baker IIRC. IIRC it can be done
> using an augmented tree, but none of that solves the problems 0-laxity
> has (like over preemption and the general problem of playing chicken by
> doing things at the *VERY* last possible moment).
> 
> I think I did a talk at OSPERT on this at some point many years ago.
> Luckily some bright fellow had this semi-partitioned stuff that would
> make live much simpler :-)

I must clarify; I was thinking Least-Laxity-First, which is ofcourse not
the same as a 0-laxity scheduler.

  parent reply	other threads:[~2023-06-19 12:02 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-08 15:58 [RFC PATCH V3 0/6] SCHED_DEADLINE server infrastructure Daniel Bristot de Oliveira
2023-06-08 15:58 ` [RFC PATCH V3 1/6] sched: Unify runtime accounting across classes Daniel Bristot de Oliveira
2023-06-13 13:24   ` Phil Auld
2023-06-16 14:30   ` Valentin Schneider
2023-06-08 15:58 ` [RFC PATCH V3 2/6] sched/deadline: Collect sched_dl_entity initialization Daniel Bristot de Oliveira
2023-06-13 13:25   ` Phil Auld
2023-06-16 14:31   ` Valentin Schneider
2023-06-08 15:58 ` [RFC PATCH V3 3/6] sched/deadline: Move bandwidth accounting into {en,de}queue_dl_entity Daniel Bristot de Oliveira
2023-06-16 14:31   ` Valentin Schneider
2023-06-08 15:58 ` [RFC PATCH V3 4/6] sched/deadline: Introduce deadline servers Daniel Bristot de Oliveira
2023-06-13 13:21   ` Phil Auld
2023-06-23 16:47   ` Valentin Schneider
2023-07-04 15:52     ` Daniel Bristot de Oliveira
2023-07-04 17:25       ` Joel Fernandes
2023-07-04 17:28         ` Joel Fernandes
2023-06-08 15:58 ` [RFC PATCH V3 5/6] sched/fair: Add trivial fair server Daniel Bristot de Oliveira
2023-06-16 12:59   ` Peter Zijlstra
2023-06-16 13:00     ` Daniel Bristot de Oliveira
2023-06-16 13:12       ` Peter Zijlstra
2023-06-16 13:18         ` Daniel Bristot de Oliveira
2023-06-08 15:58 ` [RFC PATCH V3 6/6] sched/fair: Implement starvation monitor Daniel Bristot de Oliveira
2023-06-12  1:57   ` Joel Fernandes
2023-06-12 14:45     ` Daniel Bristot de Oliveira
2023-06-12 20:35       ` Joel Fernandes
2023-06-13 13:41         ` Daniel Bristot de Oliveira
2023-06-13 15:32           ` Joel Fernandes
2023-06-14 13:45             ` Daniel Bristot de Oliveira
2023-06-14 14:15               ` Juri Lelli
2023-06-14 18:27                 ` Joel Fernandes
2023-06-14 18:24               ` Joel Fernandes
2023-06-16 12:05           ` Peter Zijlstra
2023-06-16 12:48             ` Daniel Bristot de Oliveira
2023-06-19 12:02             ` Peter Zijlstra [this message]
2023-06-19 14:58               ` Daniel Bristot de Oliveira
2023-06-16 11:56       ` Peter Zijlstra
2023-06-16 11:51   ` Peter Zijlstra
2023-06-16 13:27     ` Daniel Bristot de Oliveira

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