linux-kernel - Re: [RFC PATCH v3 02/24] sched/deadline: Distinct between dl_rq and my

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Message-ID: <aN5-QmILMDZgnU4s@jlelli-thinkpadt14gen4.remote.csb>
Date: Thu, 2 Oct 2025 14:29:38 +0100
From: Juri Lelli <juri.lelli@...hat.com>
To: Yuri Andriaccio <yurand2000@...il.com>
Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	linux-kernel@...r.kernel.org,
	Luca Abeni <luca.abeni@...tannapisa.it>,
	Yuri Andriaccio <yuri.andriaccio@...tannapisa.it>
Subject: Re: [RFC PATCH v3 02/24] sched/deadline: Distinct between dl_rq and
 my_q

Hello,

On 29/09/25 11:21, Yuri Andriaccio wrote:
> From: luca abeni <luca.abeni@...tannapisa.it>
> 
> Create two fields for runqueues in sched_dl_entity to make a distinction between
> the global runqueue and the runqueue which the dl_server serves.
> 
> Signed-off-by: luca abeni <luca.abeni@...tannapisa.it>
> Signed-off-by: Yuri Andriaccio <yurand2000@...il.com>

The change looks good to me. Maybe we only want to be a little more verbose in
the changelog, e.g. the following?

  Split the single rq pointer in sched_dl_entity into two separate
  pointers, following the existing pattern used by sched_rt_entity:

  - dl_rq: Points to the deadline runqueue where this entity is queued
  - my_q:  Points to the runqueue that this entity serves (for servers)

  This distinction is currently redundant for the fair_server (both
  point to the same CPU's structures), but is essential for future
  RT cgroup support where deadline servers will be queued on the
  global dl_rq while serving tasks from cgroup-specific runqueues.

  Update rq_of_dl_se() to use container_of() to recover the rq from
  dl_rq, and update fair.c to explicitly use my_q when accessing the
  served runqueue.

Thanks,
Juri