linux-kernel - [RFC PATCH 02/22] sched/fair: Convert "se->runnable_weight" to unsigned int and pack the struct

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Message-ID: <20250220093257.9380-3-kprateek.nayak@amd.com>
Date: Thu, 20 Feb 2025 09:32:37 +0000
From: K Prateek Nayak <kprateek.nayak@....com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot
	<vincent.guittot@...aro.org>, Valentin Schneider <vschneid@...hat.com>, "Ben
 Segall" <bsegall@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, "Andy
 Lutomirski" <luto@...nel.org>, <linux-kernel@...r.kernel.org>
CC: Dietmar Eggemann <dietmar.eggemann@....com>, Steven Rostedt
	<rostedt@...dmis.org>, Mel Gorman <mgorman@...e.de>, "Sebastian Andrzej
 Siewior" <bigeasy@...utronix.de>, Clark Williams <clrkwllms@...nel.org>,
	<linux-rt-devel@...ts.linux.dev>, Tejun Heo <tj@...nel.org>, "Frederic
 Weisbecker" <frederic@...nel.org>, Barret Rhoden <brho@...gle.com>, "Petr
 Mladek" <pmladek@...e.com>, Josh Don <joshdon@...gle.com>, Qais Yousef
	<qyousef@...alina.io>, "Paul E. McKenney" <paulmck@...nel.org>, David Vernet
	<dvernet@...a.com>, K Prateek Nayak <kprateek.nayak@....com>, "Gautham R.
 Shenoy" <gautham.shenoy@....com>, Swapnil Sapkal <swapnil.sapkal@....com>
Subject: [RFC PATCH 02/22] sched/fair: Convert "se->runnable_weight" to unsigned int and pack the struct

se->runnable_weight tracks group_cfs_rq(se)->h_nr_running which is an
unsigned int. Convert runnable_weight to an unsigned int to match the
types.

pahole notes that there is a 4 byte hole after se's "depth" member
since depth is an integer. Move depth below runnable_weight to prevent
the 4 byte hole and reclaim 8 bytes of space in total.

Signed-off-by: K Prateek Nayak <kprateek.nayak@....com>
---
 include/linux/sched.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9632e3318e0d..34862d904ea3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -569,14 +569,14 @@ struct sched_entity {
 	u64				nr_migrations;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
-	int				depth;
 	struct sched_entity		*parent;
 	/* rq on which this entity is (to be) queued: */
 	struct cfs_rq			*cfs_rq;
 	/* rq "owned" by this entity/group: */
 	struct cfs_rq			*my_q;
 	/* cached value of my_q->h_nr_running */
-	unsigned long			runnable_weight;
+	unsigned int			runnable_weight;
+	int				depth;
 #endif
 
 #ifdef CONFIG_SMP
-- 
2.43.0