1 files changed, 23 insertions, 7 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 51a7600..f84ac3f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1011,6 +1011,23 @@ migrate:
 	return migrate_task_to(p, env.best_cpu);
 }
 
+/* Attempt to migrate a task to a CPU on the preferred node. */
+static void numa_migrate_preferred(struct task_struct *p)
+{
+	/* Success if task is already running on preferred CPU */
+	p->numa_migrate_retry = 0;
+	if (cpu_to_node(task_cpu(p)) == p->numa_preferred_nid)
+		return;
+
+	/* This task has no NUMA fault statistics yet */
+	if (unlikely(p->numa_preferred_nid == -1))
+		return;
+
+	/* Otherwise, try migrate to a CPU on the preferred node */
+	if (task_numa_migrate(p) != 0)
+		p->numa_migrate_retry = jiffies + HZ*5;
+}
+
 static void task_numa_placement(struct task_struct *p)
 {
 	int seq, nid, max_nid = -1;
@@ -1045,17 +1062,12 @@ static void task_numa_placement(struct task_struct *p)
 		}
 	}
 
-	/*
-	 * Record the preferred node as the node with the most faults,
-	 * requeue the task to be running on the idlest CPU on the
-	 * preferred node and reset the scanning rate to recheck
-	 * the working set placement.
-	 */
+	/* Preferred node as the node with the most faults */
 	if (max_faults && max_nid != p->numa_preferred_nid) {
 		/* Update the preferred nid and migrate task if possible */
 		p->numa_preferred_nid = max_nid;
 		p->numa_migrate_seq = 1;
-		task_numa_migrate(p);
+		numa_migrate_preferred(p);
 	}
 }
 
@@ -1111,6 +1123,10 @@ void task_numa_fault(int last_nidpid, int node, int pages, bool migrated)
 
 	task_numa_placement(p);
 
+	/* Retry task to preferred node migration if it previously failed */
+	if (p->numa_migrate_retry && time_after(jiffies, p->numa_migrate_retry))
+		numa_migrate_preferred(p);
+
 	p->numa_faults_buffer[task_faults_idx(node, priv)] += pages;
 }