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Date:   Fri, 16 Jun 2023 15:12:43 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Daniel Bristot de Oliveira <bristot@kernel.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>
Subject: Re: [RFC PATCH V3 5/6] sched/fair: Add trivial fair server
Message-ID: <20230616131243.GO83892@hirez.programming.kicks-ass.net>
References: <cover.1686239016.git.bristot@kernel.org>
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On Fri, Jun 16, 2023 at 03:00:57PM +0200, Daniel Bristot de Oliveira wrote:
> On 6/16/23 14:59, Peter Zijlstra wrote:
> > On Thu, Jun 08, 2023 at 05:58:17PM +0200, Daniel Bristot de Oliveira wrote:
> >> +void fair_server_init(struct rq *rq)
> >> +{
> >> +	struct sched_dl_entity *dl_se = &rq->fair_server;
> >> +
> >> +	init_dl_entity(dl_se);
> >> +
> >> +	dl_se->dl_runtime = TICK_NSEC;
> >> +	dl_se->dl_deadline = 20 * TICK_NSEC;
> >> +	dl_se->dl_period = 20 * TICK_NSEC;
> >> +
> >> +	dl_server_init(dl_se, rq, fair_server_has_tasks, fair_server_pick);
> >> +}
> > 
> > These here numbers should obviously become a tunable somewhere... :-)
> 
> From sched_rt_runtime and sched_rt_period, no?

Well, probably new names. IIRC those are also limits on the whole
rt-cgroup mess, so e can't trivially change it without also ripping all
that out, and that's a little bit more work.

Ripping out the basic throttle is much simpler than replacing all that
and should be done earlier.