linux-kernel - [PATCH v2 6/8] sched/fair: Do not compute NUMA Balancing stats unnecessarily during lb

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Message-ID: <20241223043407.1611-7-kprateek.nayak@amd.com>
Date: Mon, 23 Dec 2024 04:34:05 +0000
From: K Prateek Nayak <kprateek.nayak@....com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
	Peter Zijlstra <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: "H. Peter Anvin" <hpa@...or.com>, 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>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>, Tim Chen
	<tim.c.chen@...ux.intel.com>, Shrikanth Hegde <sshegde@...ux.ibm.com>, "Mario
 Limonciello" <mario.limonciello@....com>, Meng Li <li.meng@....com>, Huang
 Rui <ray.huang@....com>, "Gautham R. Shenoy" <gautham.shenoy@....com>, "K
 Prateek Nayak" <kprateek.nayak@....com>
Subject: [PATCH v2 6/8] sched/fair: Do not compute NUMA Balancing stats unnecessarily during lb

Aggregate nr_numa_running and nr_preferred_running when load balancing
at NUMA domains only. While at it, also move the aggregation below the
idle_cpu() check since an idle CPU cannot have any preferred tasks.

Reviewed-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
Signed-off-by: K Prateek Nayak <kprateek.nayak@....com>
---
v1..v2:

o Collected tags from Vincent and Srikanth.
---
 kernel/sched/fair.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8f641c9e74a8..c68ab808d271 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10346,7 +10346,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 				      bool *sg_overloaded,
 				      bool *sg_overutilized)
 {
-	int i, nr_running, local_group;
+	int i, nr_running, local_group, sd_flags = env->sd->flags;
 
 	memset(sgs, 0, sizeof(*sgs));
 
@@ -10370,10 +10370,6 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 		if (cpu_overutilized(i))
 			*sg_overutilized = 1;
 
-#ifdef CONFIG_NUMA_BALANCING
-		sgs->nr_numa_running += rq->nr_numa_running;
-		sgs->nr_preferred_running += rq->nr_preferred_running;
-#endif
 		/*
 		 * No need to call idle_cpu() if nr_running is not 0
 		 */
@@ -10383,10 +10379,17 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 			continue;
 		}
 
+#ifdef CONFIG_NUMA_BALANCING
+		/* Only fbq_classify_group() uses this to classify NUMA groups */
+		if (sd_flags & SD_NUMA) {
+			sgs->nr_numa_running += rq->nr_numa_running;
+			sgs->nr_preferred_running += rq->nr_preferred_running;
+		}
+#endif
 		if (local_group)
 			continue;
 
-		if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
+		if (sd_flags & SD_ASYM_CPUCAPACITY) {
 			/* Check for a misfit task on the cpu */
 			if (sgs->group_misfit_task_load < rq->misfit_task_load) {
 				sgs->group_misfit_task_load = rq->misfit_task_load;
-- 
2.43.0