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Date: Wed, 5 Jun 2024 14:24:54 +0100
From: Qais Yousef <qyousef@layalina.io>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>, Metin Kaya <metin.kaya@arm.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org,
	Phil Auld <pauld@redhat.com>
Subject: Re: [PATCH v5 1/2] sched/rt: Clean up usage of rt_task()
Message-ID: <20240605132454.cjo4sjtybaeyeuze@airbuntu>
References: <20240604144228.1356121-1-qyousef@layalina.io>
 <20240604144228.1356121-2-qyousef@layalina.io>
 <b298bca1-190f-48a2-8d2c-58d54b879c72@redhat.com>
 <20240605093246.4h0kCR67@linutronix.de>
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In-Reply-To: <20240605093246.4h0kCR67@linutronix.de>

On 06/05/24 11:32, Sebastian Andrzej Siewior wrote:
> On 2024-06-04 17:57:46 [+0200], Daniel Bristot de Oliveira wrote:
> > On 6/4/24 16:42, Qais Yousef wrote:
> > > -	    (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
> > > +	    (wakeup_rt && !realtime_task(p)) ||
> > 
> > I do not like bikeshedding, and no hard feelings...

No hard feelings :-)

> > 
> > But rt is a shortened version of realtime, and so it is making *it less*
> > clear that we also have DL here.
> 
> Can SCHED_DL be considered a real-time scheduling class as in opposite
> to SCHED_BATCH for instance? Due to its requirements it fits for a real
> time scheduling class, right?
> And RT (as in real time) already includes SCHED_RR and SCHED_FIFO.

Yeah I think the usage of realtime to cover both makes sense. I followed your
precedence with task_is_realtime().

Anyway. If people really find this confusing, what would make sense is to split
them and ask users to call rt_task() and dl_task() explicitly without this
wrapper. I personally like it better with the wrapper. But happy to follow the
crowd.