4 files changed, 147 insertions, 42 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b0592bc..34bfcef 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -392,20 +392,22 @@ void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time,
 }
 EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
 
+/*
+ * should be called under rcu read lock or queue lock to make sure blkg pointer
+ * is valid.
+ */
 void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
 				uint64_t bytes, bool direction, bool sync)
 {
-	struct blkio_group_stats *stats;
-	unsigned long flags;
+	struct blkio_group_stats_cpu *stats_cpu;
 
-	spin_lock_irqsave(&blkg->stats_lock, flags);
-	stats = &blkg->stats;
-	stats->sectors += bytes >> 9;
-	blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICED], 1, direction,
-			sync);
-	blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_BYTES], bytes,
-			direction, sync);
-	spin_unlock_irqrestore(&blkg->stats_lock, flags);
+	stats_cpu = this_cpu_ptr(blkg->stats_cpu);
+
+	stats_cpu->sectors += bytes >> 9;
+	blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICED],
+			1, direction, sync);
+	blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICE_BYTES],
+			bytes, direction, sync);
 }
 EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
 
@@ -440,6 +442,20 @@ void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
 }
 EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
 
+/*
+ * This function allocates the per cpu stats for blkio_group. Should be called
+ * from sleepable context as alloc_per_cpu() requires that.
+ */
+int blkio_alloc_blkg_stats(struct blkio_group *blkg)
+{
+	/* Allocate memory for per cpu stats */
+	blkg->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu);
+	if (!blkg->stats_cpu)
+		return -ENOMEM;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(blkio_alloc_blkg_stats);
+
 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
 		struct blkio_group *blkg, void *key, dev_t dev,
 		enum blkio_policy_id plid)
@@ -600,6 +616,53 @@ static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
 	return val;
 }
 
+
+static uint64_t blkio_read_stat_cpu(struct blkio_group *blkg,
+			enum stat_type_cpu type, enum stat_sub_type sub_type)
+{
+	int cpu;
+	struct blkio_group_stats_cpu *stats_cpu;
+	uint64_t val = 0;
+
+	for_each_possible_cpu(cpu) {
+		stats_cpu  = per_cpu_ptr(blkg->stats_cpu, cpu);
+
+		if (type == BLKIO_STAT_CPU_SECTORS)
+			val += stats_cpu->sectors;
+		else
+			val += stats_cpu->stat_arr_cpu[type][sub_type];
+	}
+
+	return val;
+}
+
+static uint64_t blkio_get_stat_cpu(struct blkio_group *blkg,
+		struct cgroup_map_cb *cb, dev_t dev, enum stat_type_cpu type)
+{
+	uint64_t disk_total, val;
+	char key_str[MAX_KEY_LEN];
+	enum stat_sub_type sub_type;
+
+	if (type == BLKIO_STAT_CPU_SECTORS) {
+		val = blkio_read_stat_cpu(blkg, type, 0);
+		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, val, cb, dev);
+	}
+
+	for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
+			sub_type++) {
+		blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
+		val = blkio_read_stat_cpu(blkg, type, sub_type);
+		cb->fill(cb, key_str, val);
+	}
+
+	disk_total = blkio_read_stat_cpu(blkg, type, BLKIO_STAT_READ) +
+			blkio_read_stat_cpu(blkg, type, BLKIO_STAT_WRITE);
+
+	blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
+	cb->fill(cb, key_str, disk_total);
+	return disk_total;
+}
+
 /* This should be called with blkg->stats_lock held */
 static uint64_t blkio_get_stat(struct blkio_group *blkg,
 		struct cgroup_map_cb *cb, dev_t dev, enum stat_type type)
@@ -611,9 +674,6 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg,
 	if (type == BLKIO_STAT_TIME)
 		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 					blkg->stats.time, cb, dev);
-	if (type == BLKIO_STAT_SECTORS)
-		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
-					blkg->stats.sectors, cb, dev);
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	if (type == BLKIO_STAT_UNACCOUNTED_TIME)
 		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
@@ -1077,8 +1137,8 @@ static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
 }
 
 static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
-		struct cftype *cft, struct cgroup_map_cb *cb, enum stat_type type,
-		bool show_total)
+		struct cftype *cft, struct cgroup_map_cb *cb,
+		enum stat_type type, bool show_total, bool pcpu)
 {
 	struct blkio_group *blkg;
 	struct hlist_node *n;
@@ -1089,10 +1149,15 @@ static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
 		if (blkg->dev) {
 			if (!cftype_blkg_same_policy(cft, blkg))
 				continue;
-			spin_lock_irq(&blkg->stats_lock);
-			cgroup_total += blkio_get_stat(blkg, cb, blkg->dev,
-						type);
-			spin_unlock_irq(&blkg->stats_lock);
+			if (pcpu)
+				cgroup_total += blkio_get_stat_cpu(blkg, cb,
+						blkg->dev, type);
+			else {
+				spin_lock_irq(&blkg->stats_lock);
+				cgroup_total += blkio_get_stat(blkg, cb,
+						blkg->dev, type);
+				spin_unlock_irq(&blkg->stats_lock);
+			}
 		}
 	}
 	if (show_total)
@@ -1116,47 +1181,47 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
 		switch(name) {
 		case BLKIO_PROP_time:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_TIME, 0);
+						BLKIO_STAT_TIME, 0, 0);
 		case BLKIO_PROP_sectors:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_SECTORS, 0);
+						BLKIO_STAT_CPU_SECTORS, 0, 1);
 		case BLKIO_PROP_io_service_bytes:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_SERVICE_BYTES, 1);
+					BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1);
 		case BLKIO_PROP_io_serviced:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_SERVICED, 1);
+						BLKIO_STAT_CPU_SERVICED, 1, 1);
 		case BLKIO_PROP_io_service_time:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_SERVICE_TIME, 1);
+						BLKIO_STAT_SERVICE_TIME, 1, 0);
 		case BLKIO_PROP_io_wait_time:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_WAIT_TIME, 1);
+						BLKIO_STAT_WAIT_TIME, 1, 0);
 		case BLKIO_PROP_io_merged:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_MERGED, 1);
+						BLKIO_STAT_MERGED, 1, 0);
 		case BLKIO_PROP_io_queued:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_QUEUED, 1);
+						BLKIO_STAT_QUEUED, 1, 0);
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 		case BLKIO_PROP_unaccounted_time:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_UNACCOUNTED_TIME, 0);
+					BLKIO_STAT_UNACCOUNTED_TIME, 0, 0);
 		case BLKIO_PROP_dequeue:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_DEQUEUE, 0);
+						BLKIO_STAT_DEQUEUE, 0, 0);
 		case BLKIO_PROP_avg_queue_size:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_AVG_QUEUE_SIZE, 0);
+					BLKIO_STAT_AVG_QUEUE_SIZE, 0, 0);
 		case BLKIO_PROP_group_wait_time:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_GROUP_WAIT_TIME, 0);
+					BLKIO_STAT_GROUP_WAIT_TIME, 0, 0);
 		case BLKIO_PROP_idle_time:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_IDLE_TIME, 0);
+						BLKIO_STAT_IDLE_TIME, 0, 0);
 		case BLKIO_PROP_empty_time:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_EMPTY_TIME, 0);
+						BLKIO_STAT_EMPTY_TIME, 0, 0);
 #endif
 		default:
 			BUG();
@@ -1166,10 +1231,10 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
 		switch(name){
 		case BLKIO_THROTL_io_service_bytes:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_SERVICE_BYTES, 1);
+						BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1);
 		case BLKIO_THROTL_io_serviced:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
-						BLKIO_STAT_SERVICED, 1);
+						BLKIO_STAT_CPU_SERVICED, 1, 1);
 		default:
 			BUG();
 		}
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 63f1ef4..fd730a2 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -36,10 +36,6 @@ enum stat_type {
 	 * request completion for IOs doen by this cgroup. This may not be
 	 * accurate when NCQ is turned on. */
 	BLKIO_STAT_SERVICE_TIME = 0,
-	/* Total bytes transferred */
-	BLKIO_STAT_SERVICE_BYTES,
-	/* Total IOs serviced, post merge */
-	BLKIO_STAT_SERVICED,
 	/* Total time spent waiting in scheduler queue in ns */
 	BLKIO_STAT_WAIT_TIME,
 	/* Number of IOs merged */
@@ -48,7 +44,6 @@ enum stat_type {
 	BLKIO_STAT_QUEUED,
 	/* All the single valued stats go below this */
 	BLKIO_STAT_TIME,
-	BLKIO_STAT_SECTORS,
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	/* Time not charged to this cgroup */
 	BLKIO_STAT_UNACCOUNTED_TIME,
@@ -60,6 +55,16 @@ enum stat_type {
 #endif
 };
 
+/* Per cpu stats */
+enum stat_type_cpu {
+	BLKIO_STAT_CPU_SECTORS,
+	/* Total bytes transferred */
+	BLKIO_STAT_CPU_SERVICE_BYTES,
+	/* Total IOs serviced, post merge */
+	BLKIO_STAT_CPU_SERVICED,
+	BLKIO_STAT_CPU_NR
+};
+
 enum stat_sub_type {
 	BLKIO_STAT_READ = 0,
 	BLKIO_STAT_WRITE,
@@ -116,7 +121,6 @@ struct blkio_cgroup {
 struct blkio_group_stats {
 	/* total disk time and nr sectors dispatched by this group */
 	uint64_t time;
-	uint64_t sectors;
 	uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL];
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	/* Time not charged to this cgroup */
@@ -146,6 +150,12 @@ struct blkio_group_stats {
 #endif
 };
 
+/* Per cpu blkio group stats */
+struct blkio_group_stats_cpu {
+	uint64_t sectors;
+	uint64_t stat_arr_cpu[BLKIO_STAT_CPU_NR][BLKIO_STAT_TOTAL];
+};
+
 struct blkio_group {
 	/* An rcu protected unique identifier for the group */
 	void *key;
@@ -161,6 +171,8 @@ struct blkio_group {
 	/* Need to serialize the stats in the case of reset/update */
 	spinlock_t stats_lock;
 	struct blkio_group_stats stats;
+	/* Per cpu stats pointer */
+	struct blkio_group_stats_cpu __percpu *stats_cpu;
 };
 
 struct blkio_policy_node {
@@ -296,6 +308,7 @@ extern struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk);
 extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
 	struct blkio_group *blkg, void *key, dev_t dev,
 	enum blkio_policy_id plid);
+extern int blkio_alloc_blkg_stats(struct blkio_group *blkg);
 extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
 extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
 						void *key);
@@ -323,6 +336,8 @@ static inline void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
 		struct blkio_group *blkg, void *key, dev_t dev,
 		enum blkio_policy_id plid) {}
 
+static inline int blkio_alloc_blkg_stats(struct blkio_group *blkg) { return 0; }
+
 static inline int
 blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
 
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 90ad407..c29a5a8 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -158,6 +158,7 @@ static void throtl_free_tg(struct rcu_head *head)
 	struct throtl_grp *tg;
 
 	tg = container_of(head, struct throtl_grp, rcu_head);
+	free_percpu(tg->blkg.stats_cpu);
 	kfree(tg);
 }
 
@@ -249,11 +250,19 @@ static void throtl_init_add_tg_lists(struct throtl_data *td,
 static struct throtl_grp *throtl_alloc_tg(struct throtl_data *td)
 {
 	struct throtl_grp *tg = NULL;
+	int ret;
 
 	tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, td->queue->node);
 	if (!tg)
 		return NULL;
 
+	ret = blkio_alloc_blkg_stats(&tg->blkg);
+
+	if (ret) {
+		kfree(tg);
+		return NULL;
+	}
+
 	throtl_init_group(tg);
 	return tg;
 }
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 606020f..d646b27 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1051,7 +1051,7 @@ static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
 static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
 {
 	struct cfq_group *cfqg = NULL;
-	int i, j;
+	int i, j, ret;
 	struct cfq_rb_root *st;
 
 	cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
@@ -1069,6 +1069,13 @@ static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
 	 * or cgroup deletion path depending on who is exiting first.
 	 */
 	cfqg->ref = 1;
+
+	ret = blkio_alloc_blkg_stats(&cfqg->blkg);
+	if (ret) {
+		kfree(cfqg);
+		return NULL;
+	}
+
 	return cfqg;
 }
 
@@ -1183,6 +1190,7 @@ static void cfq_put_cfqg(struct cfq_group *cfqg)
 		return;
 	for_each_cfqg_st(cfqg, i, j, st)
 		BUG_ON(!RB_EMPTY_ROOT(&st->rb));
+	free_percpu(cfqg->blkg.stats_cpu);
 	kfree(cfqg);
 }
 
@@ -3995,7 +4003,15 @@ static void *cfq_init_queue(struct request_queue *q)
 	 * throtl_data goes away.
 	 */
 	cfqg->ref = 2;
+
+	if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
+		kfree(cfqg);
+		kfree(cfqd);
+		return NULL;
+	}
+
 	rcu_read_lock();
+
 	cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
 					(void *)cfqd, 0);
 	rcu_read_unlock();