linux-kernel - [PATCH 2/4] sched/numa: Remove the redundant member numa_group::fault

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Date:   Mon, 4 Oct 2021 16:27:04 +0530
From:   Bharata B Rao <bharata@....com>
To:     <linux-kernel@...r.kernel.org>
CC:     <mingo@...hat.com>, <peterz@...radead.org>, <mgorman@...e.de>,
        <riel@...hat.com>, Bharata B Rao <bharata@....com>
Subject: [PATCH 2/4] sched/numa: Remove the redundant member numa_group::fault_cpus

numa_group::fault_cpus is actually a pointer to the region
in numa_group::faults[] where NUMA_CPU stats are located.

Remove this redundant member and use numa_group::faults[NUMA_CPU]
directly like it is done for similar per-process numa fault stats.

There is no functionality change due to this commit.

Signed-off-by: Bharata B Rao <bharata@....com>
---
 kernel/sched/fair.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e8a696fd713d..3471c8ef0659 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1081,11 +1081,12 @@ struct numa_group {
 	unsigned long total_faults;
 	unsigned long max_faults_cpu;
 	/*
+	 * faults[] array is split into two regions: faults_mem and faults_cpu.
+	 *
 	 * Faults_cpu is used to decide whether memory should move
 	 * towards the CPU. As a consequence, these stats are weighted
 	 * more by CPU use than by memory faults.
 	 */
-	unsigned long *faults_cpu;
 	unsigned long faults[];
 };
 
@@ -1259,8 +1260,8 @@ static inline unsigned long group_faults(struct task_struct *p, int nid)
 
 static inline unsigned long group_faults_cpu(struct numa_group *group, int nid)
 {
-	return group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 0)] +
-		group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 1)];
+	return group->faults[task_faults_idx(NUMA_CPU, nid, 0)] +
+		group->faults[task_faults_idx(NUMA_CPU, nid, 1)];
 }
 
 static inline unsigned long group_faults_priv(struct numa_group *ng)
@@ -2427,7 +2428,7 @@ static void task_numa_placement(struct task_struct *p)
 				 * is at the beginning of the numa_faults array.
 				 */
 				ng->faults[mem_idx] += diff;
-				ng->faults_cpu[mem_idx] += f_diff;
+				ng->faults[cpu_idx] += f_diff;
 				ng->total_faults += diff;
 				group_faults += ng->faults[mem_idx];
 			}
@@ -2493,9 +2494,6 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
 		grp->max_faults_cpu = 0;
 		spin_lock_init(&grp->lock);
 		grp->gid = p->pid;
-		/* Second half of the array tracks nids where faults happen */
-		grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES *
-						nr_node_ids;
 
 		for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
 			grp->faults[i] = p->numa_faults[i];
-- 
2.25.1