linux-kernel - [PATCH 1/1] sched/fair: allow disabling newidle_balance with sched_relax_domain

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Date: Thu, 28 Mar 2024 02:30:18 +0200
From: Vitalii Bursov <vitaly@...sov.com>
To: Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	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>,
	Daniel Bristot de Oliveira <bristot@...hat.com>,
	Valentin Schneider <vschneid@...hat.com>,
	linux-kernel@...r.kernel.org,
	Vitalii Bursov <vitaly@...sov.com>
Subject: [PATCH 1/1] sched/fair: allow disabling newidle_balance with sched_relax_domain_level

Change relax_domain_level checks so that it would be possible
to exclude all domains from newidle balancing.

This matches the behavior described in the documentation:
  -1   no request. use system default or follow request of others.
   0   no search.
   1   search siblings (hyperthreads in a core).

"2" enables levels 0 and 1, level_max excludes the last (level_max)
level, and level_max+1 includes all levels.

Signed-off-by: Vitalii Bursov <vitaly@...sov.com>
---
 kernel/cgroup/cpuset.c  | 2 +-
 kernel/sched/debug.c    | 1 +
 kernel/sched/topology.c | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4237c874871..da24187c4e0 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2948,7 +2948,7 @@ bool current_cpuset_is_being_rebound(void)
 static int update_relax_domain_level(struct cpuset *cs, s64 val)
 {
 #ifdef CONFIG_SMP
-	if (val < -1 || val >= sched_domain_level_max)
+	if (val < -1 || val > sched_domain_level_max + 1)
 		return -EINVAL;
 #endif
 
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 8d5d98a5834..8454cd4e5e1 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -423,6 +423,7 @@ static void register_sd(struct sched_domain *sd, struct dentry *parent)
 
 #undef SDM
 
+	debugfs_create_u32("level", 0444, parent, (u32 *)&sd->level);
 	debugfs_create_file("flags", 0444, parent, &sd->flags, &sd_flags_fops);
 	debugfs_create_file("groups_flags", 0444, parent, &sd->groups->flags, &sd_flags_fops);
 }
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 99ea5986038..3127c9b30af 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1468,7 +1468,7 @@ static void set_domain_attribute(struct sched_domain *sd,
 	} else
 		request = attr->relax_domain_level;
 
-	if (sd->level > request) {
+	if (sd->level >= request) {
 		/* Turn off idle balance on this domain: */
 		sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
 	}
-- 
2.20.1