From: Lukasz Luba <lukasz.luba@arm.com>
To: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Qais Yousef <qyousef@layalina.io>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
"Rafael J. Wysocki" <rafael@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Peter Zijlstra <peterz@infradead.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
juri.lelli@redhat.com
Subject: Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins
Date: Tue, 12 Sep 2023 12:57:32 +0100 [thread overview]
Message-ID: <83b8c8d7-d53f-bea7-4ca3-5730d5c80b30@arm.com> (raw)
In-Reply-To: <7c1cedb5-6342-1bf9-d1a6-3a87f63801fc@redhat.com>
Hi Daniel,
On 9/8/23 13:51, Daniel Bristot de Oliveira wrote:
> On 9/7/23 15:45, Lukasz Luba wrote:
>>>>> RT literatur mostly methinks. Replacing WCET with a statistical model of
>>>>> sorts is not uncommon, the argument goes that not everybody will have
>>>>> their worst case at the same time and lows and highs can commonly cancel
>>>>> out and this way we can cram a little more on the system.
>>>>>
>>>>> Typically this is proposed in the context of soft-realtime systems.
>>>>
>>>> Thanks Peter, I will dive into some books...
>>>
>>> I would look at academic papers, not sure any of that ever made it to
>>> books, Daniel would know I suppose.
>>
>> Good hint, thanks!
>
> The key-words that came to my mind are:
>
> - mk-firm, where you accept m tasks will make their deadline
> every k execution - like, because you run too long.
> - mixed criticality with pWCET (probabilistic execution time) or
> average execution time + an sporadic tail execution time for
> the low criticality part.
>
> mk-firm smells like 2005's.. mixed criticality as 2015's..present.
>
> You will probably find more papers than books. Read the papers
> as a source for inspiration... not necessarily as a definitive
> solution. They generally proposed too restrictive task models.
>
> -- Daniel
>
Thanks for describing this context! That would save my time and avoid
maybe sinking in this unknown water. As you said I might tread that
as inspiration, since I don't fight with life-critical system,
but a phone which needs 'nice user experience' (hopefully there are
no people who disagree) ;)
Regards,
Lukasz
next prev parent reply other threads:[~2023-09-12 11:57 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-27 23:31 [RFC PATCH 0/7] sched: cpufreq: Remove magic margins Qais Yousef
2023-08-27 23:31 ` [RFC PATCH 1/7] sched/pelt: Add a new function to approximate the future util_avg value Qais Yousef
2023-09-06 12:56 ` Dietmar Eggemann
2023-09-06 21:19 ` Qais Yousef
2023-09-07 11:12 ` Dietmar Eggemann
2023-09-10 19:58 ` Qais Yousef
2023-09-13 17:22 ` Dietmar Eggemann
2023-09-16 19:49 ` Qais Yousef
2023-09-16 19:52 ` Qais Yousef
2023-08-27 23:31 ` [RFC PATCH 2/7] sched/pelt: Add a new function to approximate runtime to reach given util Qais Yousef
2023-09-06 12:56 ` Dietmar Eggemann
2023-09-06 20:44 ` Dietmar Eggemann
2023-09-06 21:38 ` Qais Yousef
2023-09-15 9:15 ` Hongyan Xia
2023-09-16 19:56 ` Qais Yousef
2023-08-27 23:31 ` [RFC PATCH 3/7] sched/fair: Remove magic margin in fits_capacity() Qais Yousef
2023-09-06 14:38 ` Dietmar Eggemann
2023-09-06 21:45 ` Qais Yousef
2023-08-27 23:32 ` [RFC PATCH 4/7] sched: cpufreq: Remove magic 1.25 headroom from apply_dvfs_headroom() Qais Yousef
2023-09-07 11:34 ` Peter Zijlstra
2023-09-10 19:23 ` Qais Yousef
2023-08-27 23:32 ` [RFC PATCH 5/7] sched/schedutil: Add a new tunable to dictate response time Qais Yousef
2023-09-06 21:13 ` Dietmar Eggemann
2023-09-06 21:52 ` Qais Yousef
2023-09-07 11:44 ` Peter Zijlstra
2023-09-10 19:25 ` Qais Yousef
2023-08-27 23:32 ` [RFC PATCH 6/7] sched/pelt: Introduce PELT multiplier Qais Yousef
2023-08-27 23:32 ` [RFC PATCH 7/7] cpufreq: Change default transition delay to 2ms Qais Yousef
2023-09-06 9:18 ` [RFC PATCH 0/7] sched: cpufreq: Remove magic margins Lukasz Luba
2023-09-06 21:18 ` Qais Yousef
2023-09-07 7:48 ` Lukasz Luba
2023-09-07 11:53 ` Peter Zijlstra
2023-09-07 13:06 ` Lukasz Luba
2023-09-07 13:29 ` Peter Zijlstra
2023-09-07 13:33 ` Lukasz Luba
2023-09-07 13:38 ` Peter Zijlstra
2023-09-07 13:45 ` Lukasz Luba
2023-09-08 12:51 ` Daniel Bristot de Oliveira
2023-09-12 11:57 ` Lukasz Luba [this message]
2023-09-10 18:20 ` Qais Yousef
2023-09-10 18:14 ` Qais Yousef
2023-09-07 13:26 ` Peter Zijlstra
2023-09-07 13:57 ` Lukasz Luba
2023-09-07 14:29 ` Peter Zijlstra
2023-09-07 14:42 ` Lukasz Luba
2023-09-07 20:16 ` Peter Zijlstra
2023-09-12 11:51 ` Lukasz Luba
2023-09-12 14:01 ` Vincent Guittot
2023-09-13 9:53 ` Lukasz Luba
2023-09-12 14:28 ` Peter Zijlstra
2023-09-10 19:06 ` Qais Yousef
2023-09-10 18:46 ` Qais Yousef
2023-09-07 13:08 ` Peter Zijlstra
2023-09-08 0:17 ` Qais Yousef
2023-09-08 7:40 ` Dietmar Eggemann
2023-09-08 14:07 ` Qais Yousef
2023-09-12 17:18 ` Dietmar Eggemann
2023-09-16 19:38 ` Qais Yousef
2023-09-08 10:25 ` Peter Zijlstra
2023-09-08 13:33 ` Qais Yousef
2023-09-08 13:58 ` Peter Zijlstra
2023-09-08 13:59 ` Peter Zijlstra
2023-09-08 14:11 ` Qais Yousef
2023-09-10 21:17 ` Qais Yousef
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