Linux-libre 4.8.2-gnupck-4.8.2-gnu

1 files changed, 42 insertions, 6 deletions

diff --git a/block/blk-stat.c b/block/blk-stat.c
index 8e3974d87..bdb16d84b 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -9,11 +9,29 @@
 #include "blk-stat.h"
 #include "blk-mq.h"
 
+static void blk_stat_flush_batch(struct blk_rq_stat *stat)
+{
+	if (!stat->nr_batch)
+		return;
+	if (!stat->nr_samples)
+		stat->mean = div64_s64(stat->batch, stat->nr_batch);
+	else {
+		stat->mean = div64_s64((stat->mean * stat->nr_samples) +
+					stat->batch,
+					stat->nr_samples + stat->nr_batch);
+	}
+
+	stat->nr_samples += stat->nr_batch;
+	stat->nr_batch = stat->batch = 0;
+}
+
 void blk_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
 {
 	if (!src->nr_samples)
 		return;
 
+	blk_stat_flush_batch(src);
+
 	dst->min = min(dst->min, src->min);
 	dst->max = max(dst->max, src->max);
 
@@ -31,6 +49,7 @@ static void blk_mq_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
 {
 	struct blk_mq_hw_ctx *hctx;
 	struct blk_mq_ctx *ctx;
+	uint64_t latest = 0;
 	int i, j, nr;
 
 	blk_stat_init(&dst[0]);
@@ -58,6 +77,9 @@ static void blk_mq_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
 		if (!newest)
 			break;
 
+		if (newest > latest)
+			latest = newest;
+
 		queue_for_each_hw_ctx(q, hctx, i) {
 			hctx_for_each_ctx(hctx, ctx, j) {
 				if (ctx->stat[0].time == newest) {
@@ -75,6 +97,8 @@ static void blk_mq_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
 		 * Should be very rare.
 		 */
 	} while (!nr);
+
+	dst[0].time = dst[1].time = latest;
 }
 
 void blk_queue_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
@@ -132,6 +156,7 @@ static void __blk_stat_init(struct blk_rq_stat *stat, s64 time_now)
 {
 	stat->min = -1ULL;
 	stat->max = stat->nr_samples = stat->mean = 0;
+	stat->batch = stat->nr_batch = 0;
 	stat->time = time_now & BLK_STAT_MASK;
 }
 
@@ -140,16 +165,26 @@ void blk_stat_init(struct blk_rq_stat *stat)
 	__blk_stat_init(stat, ktime_to_ns(ktime_get()));
 }
 
+static bool __blk_stat_is_current(struct blk_rq_stat *stat, s64 now)
+{
+	return (now & BLK_STAT_MASK) == (stat->time & BLK_STAT_MASK);
+}
+
+bool blk_stat_is_current(struct blk_rq_stat *stat)
+{
+	return __blk_stat_is_current(stat, ktime_to_ns(ktime_get()));
+}
+
 void blk_stat_add(struct blk_rq_stat *stat, struct request *rq)
 {
-	s64 delta, now, value;
+	s64 now, value;
 	u64 rq_time = wbt_issue_stat_get_time(&rq->wb_stat);
 
 	now = ktime_to_ns(ktime_get());
 	if (now < rq_time)
 		return;
 
-	if ((now & BLK_STAT_MASK) != (stat->time & BLK_STAT_MASK))
+	if (!__blk_stat_is_current(stat, now))
 		__blk_stat_init(stat, now);
 
 	value = now - rq_time;
@@ -158,11 +193,12 @@ void blk_stat_add(struct blk_rq_stat *stat, struct request *rq)
 	if (value < stat->min)
 		stat->min = value;
 
-	delta = value - stat->mean;
-	if (delta)
-		stat->mean += div64_s64(delta, stat->nr_samples + 1);
+	if (stat->batch + value < stat->batch ||
+	    stat->nr_batch + 1 == BLK_RQ_STAT_BATCH)
+		blk_stat_flush_batch(stat);
 
-	stat->nr_samples++;
+	stat->batch += value;
+	stat->nr_batch++;
 }
 
 void blk_stat_clear(struct request_queue *q)