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Subject: Re: [PATCH] sched/fair: vruntime should normalize when switching from
 fair
To:     Vincent Guittot <vincent.guittot@linaro.org>,
        Juri Lelli <juri.lelli@gmail.com>
Cc:     migueldedios@google.com, "Cc: Steve Muckle" <smuckle@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "Cc: Android Kernel" <kernel-team@android.com>,
        Todd Kjos <tkjos@google.com>, Paul Turner <pjt@google.com>,
        Quentin Perret <quentin.perret@arm.com>,
        Patrick Bellasi <Patrick.Bellasi@arm.com>,
        Chris Redpath <Chris.Redpath@arm.com>,
        Morten Rasmussen <Morten.Rasmussen@arm.com>,
        John Dias <joaodias@google.com>
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 <CAKfTPtCpqhQAMeQnUtuePbris0vyjmzfXo40zdprffqh9Pwv=A@mail.gmail.com>
From:   Dietmar Eggemann <dietmar.eggemann@arm.com>
Message-ID: <da0a0480-15dd-1fd3-7da9-6b60955ae729@arm.com>
Date:   Mon, 10 Sep 2018 23:24:49 -0700
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On 09/07/2018 12:58 AM, Vincent Guittot wrote:
> On Fri, 7 Sep 2018 at 09:16, Juri Lelli <juri.lelli@gmail.com> wrote:
>>
>> On 06/09/18 16:25, Dietmar Eggemann wrote:
>>> Hi Juri,
>>>
>>> On 08/23/2018 11:54 PM, Juri Lelli wrote:
>>>> On 23/08/18 18:52, Dietmar Eggemann wrote:
>>>>> Hi,
>>>>>
>>>>> On 08/21/2018 01:54 AM, Miguel de Dios wrote:
>>>>>> On 08/17/2018 11:27 AM, Steve Muckle wrote:
>>>>>>> From: John Dias <joaodias@google.com>

[...]

>>> Adding semaphores is possible but rt-app has no easy way to initialize
>>> individual objects, e.g. sem_init(..., value). The only way I see is via the
>>> global section, like "pi_enabled". But then, this is true for all objects of
>>> this kind (in this case mutexes)?
>>
>> Right, global section should work fine. Why do you think this is a
>> problem/limitation?
> 
> keep in mind that rt-app still have "ressources" section. This one is
> optional and almost never used as resources can be created on the fly
> but it's still there and can be used to initialize resources if needed
> like semaphore

I wasn't aware of that but this will do the job AFAICS. I just have to 
re-introduce the direct calls to init_foo_resource() (in this case 
init_sem_resource()) in init_resource_data() and call that instead of 
init_resource_data() for semaphores listed in the global resources section.

Example for a semaphore b_sem with initial value eq. 1:

     "resources" : {
         "b_sem" : { "type" : "sem_wait", "value" : 1 }
     }

[...]