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Subject[PATCH 9/9] numa,sched: define some magic numbers
Date
From: Rik van Riel <riel@redhat.com>

Cleanup suggested by Mel Gorman. Now the code contains some more
hints on what statistics go where.

Suggested-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Rik van Riel <riel@redhat.com>
---
kernel/sched/fair.c | 34 +++++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 43ca8c4..6b9d27c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -896,6 +896,15 @@ struct numa_group {
unsigned long faults[0];
};

+/* Shared or private faults. */
+#define NR_NUMA_HINT_FAULT_TYPES 2
+
+/* Memory and CPU locality */
+#define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2)
+
+/* Averaged statistics, and temporary buffers. */
+#define NR_NUMA_HINT_BUCKETS (NUMA_HINT_FAULT_STATS * 2)
+
pid_t task_numa_group_id(struct task_struct *p)
{
return p->numa_group ? p->numa_group->gid : 0;
@@ -903,7 +912,7 @@ pid_t task_numa_group_id(struct task_struct *p)

static inline int task_faults_idx(int nid, int priv)
{
- return 2 * nid + priv;
+ return NR_NUMA_HINT_FAULT_TYPES * nid + priv;
}

static inline unsigned long task_faults(struct task_struct *p, int nid)
@@ -1514,7 +1523,7 @@ static void task_numa_placement(struct task_struct *p)
unsigned long faults = 0, group_faults = 0;
int priv, i;

- for (priv = 0; priv < 2; priv++) {
+ for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) {
long diff, f_diff, f_weight;

i = task_faults_idx(nid, priv);
@@ -1625,11 +1634,12 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
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;
+ grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES *
+ nr_node_ids;

node_set(task_node(current), grp->active_nodes);

- for (i = 0; i < 4*nr_node_ids; i++)
+ for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
grp->faults[i] = p->numa_faults_memory[i];

grp->total_faults = p->total_numa_faults;
@@ -1687,7 +1697,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,

double_lock(&my_grp->lock, &grp->lock);

- for (i = 0; i < 4*nr_node_ids; i++) {
+ for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
my_grp->faults[i] -= p->numa_faults_memory[i];
grp->faults[i] += p->numa_faults_memory[i];
}
@@ -1726,7 +1736,7 @@ void task_numa_free(struct task_struct *p)

if (grp) {
spin_lock(&grp->lock);
- for (i = 0; i < 4*nr_node_ids; i++)
+ for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
grp->faults[i] -= p->numa_faults_memory[i];
grp->total_faults -= p->total_numa_faults;

@@ -1767,14 +1777,20 @@ void task_numa_fault(int last_cpupid, int mem_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) * 4 * nr_node_ids;
+ int size = sizeof(*p->numa_faults_memory) *
+ NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids;

- /* numa_faults and numa_faults_buffer share the allocation */
- p->numa_faults_memory = kzalloc(size * 2, GFP_KERNEL|__GFP_NOWARN);
+ p->numa_faults_memory = kzalloc(size, GFP_KERNEL|__GFP_NOWARN);
if (!p->numa_faults_memory)
return;

BUG_ON(p->numa_faults_buffer_memory);
+ /*
+ * The averaged statistics, shared & private, memory & cpu,
+ * occupy the first half of the array. The second half of the
+ * array is for current counters, which are averaged into the
+ * first set by task_numa_placement.
+ */
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);
--
1.8.4.2


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