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Subject[PATCH 62/63] sched: numa: use unsigned longs for numa group fault stats
Date
As Peter says "If you're going to hold locks you can also do away with all
that atomic_long_*() nonsense". Lock aquisition moved slightly to protect
the updates.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
kernel/sched/fair.c | 49 ++++++++++++++++++++-----------------------------
1 file changed, 20 insertions(+), 29 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c00611c..fced601 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -916,8 +916,8 @@ struct numa_group {
struct list_head task_list;

struct rcu_head rcu;
- atomic_long_t total_faults;
- atomic_long_t faults[0];
+ unsigned long total_faults;
+ unsigned long faults[0];
};

pid_t task_numa_group_id(struct task_struct *p)
@@ -944,8 +944,7 @@ static inline unsigned long group_faults(struct task_struct *p, int nid)
if (!p->numa_group)
return 0;

- return atomic_long_read(&p->numa_group->faults[2*nid]) +
- atomic_long_read(&p->numa_group->faults[2*nid+1]);
+ return p->numa_group->faults[2*nid] + p->numa_group->faults[2*nid+1];
}

/*
@@ -971,17 +970,10 @@ static inline unsigned long task_weight(struct task_struct *p, int nid)

static inline unsigned long group_weight(struct task_struct *p, int nid)
{
- unsigned long total_faults;
-
- if (!p->numa_group)
- return 0;
-
- total_faults = atomic_long_read(&p->numa_group->total_faults);
-
- if (!total_faults)
+ if (!p->numa_group || !p->numa_group->total_faults)
return 0;

- return 1000 * group_faults(p, nid) / total_faults;
+ return 1000 * group_faults(p, nid) / p->numa_group->total_faults;
}

static unsigned long weighted_cpuload(const int cpu);
@@ -1397,9 +1389,9 @@ static void task_numa_placement(struct task_struct *p)
p->total_numa_faults += diff;
if (p->numa_group) {
/* safe because we can only change our own group */
- atomic_long_add(diff, &p->numa_group->faults[i]);
- atomic_long_add(diff, &p->numa_group->total_faults);
- group_faults += atomic_long_read(&p->numa_group->faults[i]);
+ p->numa_group->faults[i] += diff;
+ p->numa_group->total_faults += diff;
+ group_faults += p->numa_group->faults[i];
}
}

@@ -1475,7 +1467,7 @@ 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(atomic_long_t);
+ 2*nr_node_ids*sizeof(unsigned long);

grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
if (!grp)
@@ -1487,9 +1479,9 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
grp->gid = p->pid;

for (i = 0; i < 2*nr_node_ids; i++)
- atomic_long_set(&grp->faults[i], p->numa_faults[i]);
+ grp->faults[i] = p->numa_faults[i];

- atomic_long_set(&grp->total_faults, p->total_numa_faults);
+ grp->total_faults = p->total_numa_faults;

list_add(&p->numa_entry, &grp->task_list);
grp->nr_tasks++;
@@ -1543,14 +1535,14 @@ unlock:
if (!join)
return;

+ double_lock(&my_grp->lock, &grp->lock);
+
for (i = 0; i < 2*nr_node_ids; i++) {
- atomic_long_sub(p->numa_faults[i], &my_grp->faults[i]);
- atomic_long_add(p->numa_faults[i], &grp->faults[i]);
+ my_grp->faults[i] -= p->numa_faults[i];
+ grp->faults[i] += p->numa_faults[i];
}
- atomic_long_sub(p->total_numa_faults, &my_grp->total_faults);
- atomic_long_add(p->total_numa_faults, &grp->total_faults);
-
- double_lock(&my_grp->lock, &grp->lock);
+ my_grp->total_faults -= p->total_numa_faults;
+ grp->total_faults += p->total_numa_faults;

list_move(&p->numa_entry, &grp->task_list);
my_grp->nr_tasks--;
@@ -1571,12 +1563,11 @@ void task_numa_free(struct task_struct *p)
void *numa_faults = p->numa_faults;

if (grp) {
+ spin_lock(&grp->lock);
for (i = 0; i < 2*nr_node_ids; i++)
- atomic_long_sub(p->numa_faults[i], &grp->faults[i]);
-
- atomic_long_sub(p->total_numa_faults, &grp->total_faults);
+ grp->faults[i] -= p->numa_faults[i];
+ grp->total_faults -= p->total_numa_faults;

- spin_lock(&grp->lock);
list_del(&p->numa_entry);
grp->nr_tasks--;
spin_unlock(&grp->lock);
--
1.8.1.4


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