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Message-ID: <59203a63-f759-431c-a035-d3cbc433dcfb@kernel.org>
Date:   Mon, 6 Nov 2023 15:26:52 +0100
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Subject: Re: [PATCH v5 5/7] sched/fair: Add trivial fair server
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     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>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        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>,
        Joel Fernandes <joel@joelfernandes.org>,
        Vineeth Pillai <vineeth@bitbyteword.org>,
        Shuah Khan <skhan@linuxfoundation.org>,
        Phil Auld <pauld@redhat.com>
References: <cover.1699095159.git.bristot@kernel.org>
 <4e0d14eb6e0ec33055197ac7ddb57ef7ab3894a5.1699095159.git.bristot@kernel.org>
 <20231106142430.GF3818@noisy.programming.kicks-ass.net>
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From:   Daniel Bristot de Oliveira <bristot@kernel.org>
In-Reply-To: <20231106142430.GF3818@noisy.programming.kicks-ass.net>
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On 11/6/23 15:24, Peter Zijlstra wrote:
> On Sat, Nov 04, 2023 at 11:59:22AM +0100, Daniel Bristot de Oliveira wrote:
> 
>> [ dl_server do not account for rt ]
>> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>> index 541d547e1019..1d7b96ca9011 100644
>> --- a/kernel/sched/deadline.c
>> +++ b/kernel/sched/deadline.c
>> @@ -1382,6 +1382,13 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64
>>  			resched_curr(rq);
>>  	}
>>  
>> +	/*
>> +	 * The fair server (sole dl_server) does not account for real-time
>> +	 * workload because it is running fair work.
>> +	 */
>> +	if (dl_server(dl_se))
>> +		return;
>> +
>>  	/*
>>  	 * Because -- for now -- we share the rt bandwidth, we need to
>>  	 * account our runtime there too, otherwise actual rt tasks
> Should we perhaps write this like so?
> 
> 	if (dl_se == &rq->fair_server)
> 		return;

right, it is better for the next step (making it generic).

-- Daniel