linux-kernel - Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins

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Message-ID: <8657cc7c-169b-3479-5919-72bd39335b15@arm.com>
Date:   Thu, 7 Sep 2023 14:45:30 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Qais Yousef <qyousef@...alina.io>, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rafael@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>, bristot@...hat.com,
        juri.lelli@...hat.com
Subject: Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins



On 9/7/23 14:38, Peter Zijlstra wrote:
> On Thu, Sep 07, 2023 at 02:33:49PM +0100, Lukasz Luba wrote:
>>
>>
>> On 9/7/23 14:29, Peter Zijlstra wrote:
>>> On Thu, Sep 07, 2023 at 02:06:15PM +0100, Lukasz Luba wrote:
>>>
>>>>> Many extentions to the periodic task model are possible, including
>>>>> things like average runtime with bursts etc.. all have their trade-offs.
>>>>
>>>> Was that maybe proposed somewhere on LKML (the other models)?
>>>
>>> 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!