sched/numa: Track from which nodes NUMA faults are triggered

Track which nodes NUMA faults are triggered from, in other words
the CPUs on which the NUMA faults happened. This uses a similar
mechanism to what is used to track the memory involved in numa faults.

The next patches use this to build up a bitmap of which nodes a
workload is actively running on.

Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chegu Vinod <chegu_vinod@hp.com>
Link: http://lkml.kernel.org/r/1390860228-21539-4-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 30 insertions, 9 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 144d509df053..5fb0cfb43ecf 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1480,6 +1480,13 @@ struct task_struct {
         unsigned long *numa_faults_buffer_memory;
 
         /*
+         * Track the nodes the process was running on when a NUMA hinting
+         * fault was incurred.
+         */
+        unsigned long *numa_faults_cpu;
+        unsigned long *numa_faults_buffer_cpu;
+
+        /*
          * numa_faults_locality tracks if faults recorded during the last
          * scan window were remote/local. The task scan period is adapted
          * based on the locality of the faults with different weights
@@ -1582,8 +1589,6 @@ extern void task_numa_fault(int last_node, int node, int pages, int flags);
 extern pid_t task_numa_group_id(struct task_struct *p);
 extern void set_numabalancing_state(bool enabled);
 extern void task_numa_free(struct task_struct *p);
-
-extern unsigned int sysctl_numa_balancing_migrate_deferred;
 #else
 static inline void task_numa_fault(int last_node, int node, int pages,
                                    int flags)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3e616d704f67..4841aaff7394 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -886,6 +886,7 @@ struct numa_group {
 
         struct rcu_head rcu;
         unsigned long total_faults;
+        unsigned long *faults_cpu;
         unsigned long faults[0];
 };
 
@@ -1368,10 +1369,11 @@ static void task_numa_placement(struct task_struct *p)
                 int priv, i;
 
                 for (priv = 0; priv < 2; priv++) {
-                        long diff;
+                        long diff, f_diff;
 
                         i = task_faults_idx(nid, priv);
                         diff = -p->numa_faults_memory[i];
+                        f_diff = -p->numa_faults_cpu[i];
 
                         /* Decay existing window, copy faults since last scan */
                         p->numa_faults_memory[i] >>= 1;
@@ -1379,12 +1381,18 @@ static void task_numa_placement(struct task_struct *p)
                         fault_types[priv] += p->numa_faults_buffer_memory[i];
                         p->numa_faults_buffer_memory[i] = 0;
 
+                        p->numa_faults_cpu[i] >>= 1;
+                        p->numa_faults_cpu[i] += p->numa_faults_buffer_cpu[i];
+                        p->numa_faults_buffer_cpu[i] = 0;
+
                         faults += p->numa_faults_memory[i];
                         diff += p->numa_faults_memory[i];
+                        f_diff += p->numa_faults_cpu[i];
                         p->total_numa_faults += diff;
                         if (p->numa_group) {
                                 /* safe because we can only change our own group */
                                 p->numa_group->faults[i] += diff;
+                                p->numa_group->faults_cpu[i] += f_diff;
                                 p->numa_group->total_faults += diff;
                                 group_faults += p->numa_group->faults[i];
                         }
@@ -1453,7 +1461,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
 
         if (unlikely(!p->numa_group)) {
                 unsigned int size = sizeof(struct numa_group) +
-                                    2*nr_node_ids*sizeof(unsigned long);
+                                    4*nr_node_ids*sizeof(unsigned long);
 
                 grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
                 if (!grp)
@@ -1463,8 +1471,10 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
                 spin_lock_init(&grp->lock);
                 INIT_LIST_HEAD(&grp->task_list);
                 grp->gid = p->pid;
+                /* Second half of the array tracks nids where faults happen */
+                grp->faults_cpu = grp->faults + 2 * nr_node_ids;
 
-                for (i = 0; i < 2*nr_node_ids; i++)
+                for (i = 0; i < 4*nr_node_ids; i++)
                         grp->faults[i] = p->numa_faults_memory[i];
 
                 grp->total_faults = p->total_numa_faults;
@@ -1522,7 +1532,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
 
         double_lock(&my_grp->lock, &grp->lock);
 
-        for (i = 0; i < 2*nr_node_ids; i++) {
+        for (i = 0; i < 4*nr_node_ids; i++) {
                 my_grp->faults[i] -= p->numa_faults_memory[i];
                 grp->faults[i] += p->numa_faults_memory[i];
         }
@@ -1554,7 +1564,7 @@ void task_numa_free(struct task_struct *p)
 
         if (grp) {
                 spin_lock(&grp->lock);
-                for (i = 0; i < 2*nr_node_ids; i++)
+                for (i = 0; i < 4*nr_node_ids; i++)
                         grp->faults[i] -= p->numa_faults_memory[i];
                 grp->total_faults -= p->total_numa_faults;
 
@@ -1567,6 +1577,8 @@ void task_numa_free(struct task_struct *p)
 
         p->numa_faults_memory = NULL;
         p->numa_faults_buffer_memory = NULL;
+        p->numa_faults_cpu= NULL;
+        p->numa_faults_buffer_cpu = NULL;
         kfree(numa_faults);
 }
 
@@ -1577,6 +1589,7 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags)
 {
         struct task_struct *p = current;
         bool migrated = flags & TNF_MIGRATED;
+        int this_node = task_node(current);
         int priv;
 
         if (!numabalancing_enabled)
@@ -1592,7 +1605,7 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags)
 
         /* Allocate buffer to track faults on a per-node basis */
         if (unlikely(!p->numa_faults_memory)) {
-                int size = sizeof(*p->numa_faults_memory) * 2 * nr_node_ids;
+                int size = sizeof(*p->numa_faults_memory) * 4 * nr_node_ids;
 
                 /* numa_faults and numa_faults_buffer share the allocation */
                 p->numa_faults_memory = kzalloc(size * 2, GFP_KERNEL|__GFP_NOWARN);
@@ -1600,7 +1613,9 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags)
                         return;
 
                 BUG_ON(p->numa_faults_buffer_memory);
-                p->numa_faults_buffer_memory = p->numa_faults_memory + (2 * nr_node_ids);
+                p->numa_faults_cpu = p->numa_faults_memory + (2 * nr_node_ids);
+                p->numa_faults_buffer_memory = p->numa_faults_memory + (4 * nr_node_ids);
+                p->numa_faults_buffer_cpu = p->numa_faults_memory + (6 * nr_node_ids);
                 p->total_numa_faults = 0;
                 memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
         }
@@ -1630,6 +1645,7 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags)
                 p->numa_pages_migrated += pages;
 
         p->numa_faults_buffer_memory[task_faults_idx(node, priv)] += pages;
+        p->numa_faults_buffer_cpu[task_faults_idx(this_node, priv)] += pages;
         p->numa_faults_locality[!!(flags & TNF_FAULT_LOCAL)] += pages;
 }