1 files changed, 149 insertions, 6 deletions

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 23b173e34591..f30f9b37fcf0 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -431,6 +431,14 @@ struct ioc {
 	bool				user_cost_model:1;
 };
 
+struct iocg_pcpu_stat {
+	local64_t			abs_vusage;
+};
+
+struct iocg_stat {
+	u64				usage_us;
+};
+
 /* per device-cgroup pair */
 struct ioc_gq {
 	struct blkg_policy_data		pd;
@@ -492,10 +500,19 @@ struct ioc_gq {
 	u32				hweight_inuse;
 	bool				has_surplus;
 
+	struct list_head		walk_list;
+
 	struct wait_queue_head		waitq;
 	struct hrtimer			waitq_timer;
 	struct hrtimer			delay_timer;
 
+	/* statistics */
+	struct iocg_pcpu_stat __percpu	*pcpu_stat;
+	struct iocg_stat		local_stat;
+	struct iocg_stat		desc_stat;
+	struct iocg_stat		last_stat;
+	u64				last_stat_abs_vusage;
+
 	/* usage is recorded as fractions of WEIGHT_ONE */
 	int				usage_idx;
 	u32				usages[NR_USAGE_SLOTS];
@@ -674,10 +691,17 @@ static u64 cost_to_abs_cost(u64 cost, u32 hw_inuse)
 	return DIV64_U64_ROUND_UP(cost * hw_inuse, WEIGHT_ONE);
 }
 
-static void iocg_commit_bio(struct ioc_gq *iocg, struct bio *bio, u64 cost)
+static void iocg_commit_bio(struct ioc_gq *iocg, struct bio *bio,
+			    u64 abs_cost, u64 cost)
 {
+	struct iocg_pcpu_stat *gcs;
+
 	bio->bi_iocost_cost = cost;
 	atomic64_add(cost, &iocg->vtime);
+
+	gcs = get_cpu_ptr(iocg->pcpu_stat);
+	local64_add(abs_cost, &gcs->abs_vusage);
+	put_cpu_ptr(gcs);
 }
 
 static void iocg_lock(struct ioc_gq *iocg, bool lock_ioc, unsigned long *flags)
@@ -1221,7 +1245,7 @@ static int iocg_wake_fn(struct wait_queue_entry *wq_entry, unsigned mode,
 	if (ctx->vbudget < 0)
 		return -1;
 
-	iocg_commit_bio(ctx->iocg, wait->bio, cost);
+	iocg_commit_bio(ctx->iocg, wait->bio, wait->abs_cost, cost);
 
 	/*
 	 * autoremove_wake_function() removes the wait entry only when it
@@ -1382,6 +1406,87 @@ static bool iocg_is_idle(struct ioc_gq *iocg)
 	return true;
 }
 
+/*
+ * Call this function on the target leaf @iocg's to build pre-order traversal
+ * list of all the ancestors in @inner_walk. The inner nodes are linked through
+ * ->walk_list and the caller is responsible for dissolving the list after use.
+ */
+static void iocg_build_inner_walk(struct ioc_gq *iocg,
+				  struct list_head *inner_walk)
+{
+	int lvl;
+
+	WARN_ON_ONCE(!list_empty(&iocg->walk_list));
+
+	/* find the first ancestor which hasn't been visited yet */
+	for (lvl = iocg->level - 1; lvl >= 0; lvl--) {
+		if (!list_empty(&iocg->ancestors[lvl]->walk_list))
+			break;
+	}
+
+	/* walk down and visit the inner nodes to get pre-order traversal */
+	while (++lvl <= iocg->level - 1) {
+		struct ioc_gq *inner = iocg->ancestors[lvl];
+
+		/* record traversal order */
+		list_add_tail(&inner->walk_list, inner_walk);
+	}
+}
+
+/* collect per-cpu counters and propagate the deltas to the parent */
+static void iocg_flush_stat_one(struct ioc_gq *iocg, struct ioc_now *now)
+{
+	struct iocg_stat new_stat;
+	u64 abs_vusage = 0;
+	u64 vusage_delta;
+	int cpu;
+
+	lockdep_assert_held(&iocg->ioc->lock);
+
+	/* collect per-cpu counters */
+	for_each_possible_cpu(cpu) {
+		abs_vusage += local64_read(
+				per_cpu_ptr(&iocg->pcpu_stat->abs_vusage, cpu));
+	}
+	vusage_delta = abs_vusage - iocg->last_stat_abs_vusage;
+	iocg->last_stat_abs_vusage = abs_vusage;
+
+	iocg->local_stat.usage_us += div64_u64(vusage_delta, now->vrate);
+
+	new_stat.usage_us =
+		iocg->local_stat.usage_us + iocg->desc_stat.usage_us;
+
+	/* propagate the deltas to the parent */
+	if (iocg->level > 0) {
+		struct iocg_stat *parent_stat =
+			&iocg->ancestors[iocg->level - 1]->desc_stat;
+
+		parent_stat->usage_us +=
+			new_stat.usage_us - iocg->last_stat.usage_us;
+	}
+
+	iocg->last_stat = new_stat;
+}
+
+/* get stat counters ready for reading on all active iocgs */
+static void iocg_flush_stat(struct list_head *target_iocgs, struct ioc_now *now)
+{
+	LIST_HEAD(inner_walk);
+	struct ioc_gq *iocg, *tiocg;
+
+	/* flush leaves and build inner node walk list */
+	list_for_each_entry(iocg, target_iocgs, active_list) {
+		iocg_flush_stat_one(iocg, now);
+		iocg_build_inner_walk(iocg, &inner_walk);
+	}
+
+	/* keep flushing upwards by walking the inner list backwards */
+	list_for_each_entry_safe_reverse(iocg, tiocg, &inner_walk, walk_list) {
+		iocg_flush_stat_one(iocg, now);
+		list_del_init(&iocg->walk_list);
+	}
+}
+
 /* returns usage with margin added if surplus is large enough */
 static u32 surplus_adjusted_hweight_inuse(u32 usage, u32 hw_inuse)
 {
@@ -1422,6 +1527,8 @@ static void ioc_timer_fn(struct timer_list *timer)
 		return;
 	}
 
+	iocg_flush_stat(&ioc->active_iocgs, &now);
+
 	/*
 	 * Waiters determine the sleep durations based on the vrate they
 	 * saw at the time of sleep.  If vrate has increased, some waiters
@@ -1824,7 +1931,7 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio)
 	 */
 	if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt &&
 	    time_before_eq64(vtime + cost, now.vnow)) {
-		iocg_commit_bio(iocg, bio, cost);
+		iocg_commit_bio(iocg, bio, abs_cost, cost);
 		return;
 	}
 
@@ -1849,7 +1956,7 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio)
 	 */
 	if (unlikely(list_empty(&iocg->active_list))) {
 		iocg_unlock(iocg, ioc_locked, &flags);
-		iocg_commit_bio(iocg, bio, cost);
+		iocg_commit_bio(iocg, bio, abs_cost, cost);
 		return;
 	}
 
@@ -1948,7 +2055,7 @@ static void ioc_rqos_merge(struct rq_qos *rqos, struct request *rq,
 	 */
 	if (rq->bio && rq->bio->bi_iocost_cost &&
 	    time_before_eq64(atomic64_read(&iocg->vtime) + cost, now.vnow)) {
-		iocg_commit_bio(iocg, bio, cost);
+		iocg_commit_bio(iocg, bio, abs_cost, cost);
 		return;
 	}
 
@@ -1962,7 +2069,7 @@ static void ioc_rqos_merge(struct rq_qos *rqos, struct request *rq,
 		iocg->abs_vdebt += abs_cost;
 		iocg_kick_delay(iocg, &now);
 	} else {
-		iocg_commit_bio(iocg, bio, cost);
+		iocg_commit_bio(iocg, bio, abs_cost, cost);
 	}
 	spin_unlock_irqrestore(&iocg->waitq.lock, flags);
 }
@@ -2133,6 +2240,12 @@ static struct blkg_policy_data *ioc_pd_alloc(gfp_t gfp, struct request_queue *q,
 	if (!iocg)
 		return NULL;
 
+	iocg->pcpu_stat = alloc_percpu_gfp(struct iocg_pcpu_stat, gfp);
+	if (!iocg->pcpu_stat) {
+		kfree(iocg);
+		return NULL;
+	}
+
 	return &iocg->pd;
 }
 
@@ -2152,6 +2265,7 @@ static void ioc_pd_init(struct blkg_policy_data *pd)
 	atomic64_set(&iocg->done_vtime, now.vnow);
 	atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period));
 	INIT_LIST_HEAD(&iocg->active_list);
+	INIT_LIST_HEAD(&iocg->walk_list);
 	iocg->hweight_active = WEIGHT_ONE;
 	iocg->hweight_inuse = WEIGHT_ONE;
 
@@ -2181,18 +2295,46 @@ static void ioc_pd_free(struct blkg_policy_data *pd)
 
 	if (ioc) {
 		spin_lock_irqsave(&ioc->lock, flags);
+
 		if (!list_empty(&iocg->active_list)) {
 			propagate_weights(iocg, 0, 0);
 			list_del_init(&iocg->active_list);
 		}
+
+		WARN_ON_ONCE(!list_empty(&iocg->walk_list));
+
 		spin_unlock_irqrestore(&ioc->lock, flags);
 
 		hrtimer_cancel(&iocg->waitq_timer);
 		hrtimer_cancel(&iocg->delay_timer);
 	}
+	free_percpu(iocg->pcpu_stat);
 	kfree(iocg);
 }
 
+static size_t ioc_pd_stat(struct blkg_policy_data *pd, char *buf, size_t size)
+{
+	struct ioc_gq *iocg = pd_to_iocg(pd);
+	struct ioc *ioc = iocg->ioc;
+	size_t pos = 0;
+
+	if (!ioc->enabled)
+		return 0;
+
+	if (iocg->level == 0) {
+		unsigned vp10k = DIV64_U64_ROUND_CLOSEST(
+			atomic64_read(&ioc->vtime_rate) * 10000,
+			VTIME_PER_USEC);
+		pos += scnprintf(buf + pos, size - pos, " cost.vrate=%u.%02u",
+				  vp10k / 100, vp10k % 100);
+	}
+
+	pos += scnprintf(buf + pos, size - pos, " cost.usage=%llu",
+			 iocg->last_stat.usage_us);
+
+	return pos;
+}
+
 static u64 ioc_weight_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
 			     int off)
 {
@@ -2606,6 +2748,7 @@ static struct blkcg_policy blkcg_policy_iocost = {
 	.pd_alloc_fn	= ioc_pd_alloc,
 	.pd_init_fn	= ioc_pd_init,
 	.pd_free_fn	= ioc_pd_free,
+	.pd_stat_fn	= ioc_pd_stat,
 };
 
 static int __init ioc_init(void)