linux-kernel - [PATCH v3 2/2] sched/fair: Use helper functions to access rd->overload

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Date: Mon, 25 Mar 2024 11:15:05 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: mingo@...nel.org, peterz@...radead.org, vincent.guittot@...aro.org
Cc: sshegde@...ux.ibm.com, dietmar.eggemann@....com, qyousef@...alina.io,
        linux-kernel@...r.kernel.org, vschneid@...hat.com
Subject: [PATCH v3 2/2] sched/fair: Use helper functions to access rd->overload

rd->overload is accessed at multiple places. Instead it could use helper
get/set functions. This would make the code more readable and easy to
maintain.

No change in functionality intended.

Suggested-by: Qais Yousef <qyousef@...alina.io>
Signed-off-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
Reviewed-by: Qais Yousef <qyousef@...alina.io>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
---
 kernel/sched/fair.c  |  5 ++---
 kernel/sched/sched.h | 14 ++++++++++++--
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index eeebadd7d9ae..f00cb66cc479 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10621,8 +10621,7 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd

 	if (!env->sd->parent) {
 		/* update overload indicator if we are at root domain */
-		if (READ_ONCE(env->dst_rq->rd->overload) != (sg_status & SG_OVERLOAD))
-			WRITE_ONCE(env->dst_rq->rd->overload, sg_status & SG_OVERLOAD);
+		set_rd_overload_status(env->dst_rq->rd, sg_status & SG_OVERLOAD);

 		/* Update over-utilization (tipping point, U >= 0) indicator */
 		set_rd_overutilized_status(env->dst_rq->rd,
@@ -12344,7 +12343,7 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf)
 	rcu_read_lock();
 	sd = rcu_dereference_check_sched_domain(this_rq->sd);

-	if (!READ_ONCE(this_rq->rd->overload) ||
+	if (!is_rd_overloaded(this_rq->rd) ||
 	    (sd && this_rq->avg_idle < sd->max_newidle_lb_cost)) {

 		if (sd)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 41024c1c49b4..bed5ad8a1827 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -918,6 +918,17 @@ extern void rq_attach_root(struct rq *rq, struct root_domain *rd);
 extern void sched_get_rd(struct root_domain *rd);
 extern void sched_put_rd(struct root_domain *rd);

+static inline int is_rd_overloaded(struct root_domain *rd)
+{
+	return READ_ONCE(rd->overload);
+}
+
+static inline void set_rd_overload_status(struct root_domain *rd, int status)
+{
+	if (is_rd_overloaded(rd) != status)
+		WRITE_ONCE(rd->overload, status);
+}
+
 #ifdef HAVE_RT_PUSH_IPI
 extern void rto_push_irq_work_func(struct irq_work *work);
 #endif
@@ -2518,8 +2529,7 @@ static inline void add_nr_running(struct rq *rq, unsigned count)

 #ifdef CONFIG_SMP
 	if (prev_nr < 2 && rq->nr_running >= 2) {
-		if (!READ_ONCE(rq->rd->overload))
-			WRITE_ONCE(rq->rd->overload, 1);
+		set_rd_overload_status(rq->rd, SG_OVERLOAD);
 	}
 #endif

--
2.39.3