diff --git a/block/blk-core.c b/block/blk-core.c
index 7b6d5c8c036f00bd543ed04b5c39e67bae92dfc3..a4ec5e168312f455faebbc66fe191b78a80967cc 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -62,6 +62,21 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
 
 DEFINE_IDA(blk_queue_ida);
 
+bool precise_iostat;
+
+static int __init precise_iostat_setup(char *str)
+{
+	bool precise;
+
+	if (!strtobool(str, &precise)) {
+		precise_iostat = precise;
+		pr_info("precise iostat %d\n", precise_iostat);
+	}
+
+	return 1;
+}
+__setup("precise_iostat=", precise_iostat_setup);
+
 /*
  * For queue allocation
  */
@@ -1258,9 +1273,14 @@ void update_io_ticks(struct hd_struct *part, unsigned long now, bool end)
 	unsigned long stamp;
 again:
 	stamp = READ_ONCE(part->stamp);
-	if (unlikely(time_after(now, stamp))) {
-		if (likely(cmpxchg(&part->stamp, stamp, now) == stamp))
+	if (unlikely(time_after(now, stamp)) &&
+		likely(cmpxchg(&part->stamp, stamp, now) == stamp)) {
+		if (precise_iostat) {
+			if (end || part_in_flight(part))
+				__part_stat_add(part, io_ticks, now - stamp);
+		} else {
 			__part_stat_add(part, io_ticks, end ? now - stamp : 1);
+		}
 	}
 	if (part->partno) {
 		part = &part_to_disk(part)->part0;
@@ -1318,6 +1338,8 @@ void blk_account_io_done(struct request *req, u64 now)
 #else
 		part_stat_add(part, nsecs[sgrp], now - req->start_time_ns);
 #endif
+		if (precise_iostat)
+			part_stat_local_dec(part, in_flight[rq_data_dir(req)]);
 		part_stat_unlock();
 
 		hd_struct_put(part);
@@ -1333,6 +1355,8 @@ void blk_account_io_start(struct request *rq)
 
 	part_stat_lock();
 	update_io_ticks(rq->part, jiffies, false);
+	if (precise_iostat)
+		part_stat_local_inc(rq->part, in_flight[rq_data_dir(rq)]);
 	part_stat_unlock();
 }
 
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 6518e0ae283516039419341010e242fe7d69654f..cfb88d2fbf389a8ee16a861d01c127d721d56624 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -696,6 +696,8 @@ static void blk_account_io_merge_request(struct request *req)
 	if (blk_do_io_stat(req)) {
 		part_stat_lock();
 		part_stat_inc(req->part, merges[op_stat_group(req_op(req))]);
+		if (precise_iostat)
+			part_stat_local_dec(req->part, in_flight[rq_data_dir(req)]);
 		part_stat_unlock();
 
 		hd_struct_put(req->part);
diff --git a/block/genhd.c b/block/genhd.c
index 021c9c2d7231ae1fad4f656be0c48bac7b14d675..4f6a0be74d852626de49dba5ccb3b5772610370d 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -112,7 +112,7 @@ static void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
 	}
 }
 
-static unsigned int part_in_flight(struct hd_struct *part)
+unsigned int part_in_flight(struct hd_struct *part)
 {
 	unsigned int inflight = 0;
 	int cpu;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 58475edd65f4cfffeddbb6606f9c3581100734f8..e4bcb11d6202622dfb5c182539516cfb136f7800 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -29,6 +29,7 @@
 #include <linux/pm.h>
 #include <linux/sbitmap.h>
 
+extern bool precise_iostat;
 struct module;
 struct scsi_ioctl_command;
 
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 05927a1c6b5b18c8ae00626edfc65ccdca7cc998..959add98b6865aa42e66132df25e55b4b94894a4 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -304,6 +304,7 @@ extern void disk_part_iter_exit(struct disk_part_iter *piter);
 extern bool disk_has_partitions(struct gendisk *disk);
 
 /* block/genhd.c */
+extern unsigned int part_in_flight(struct hd_struct *part);
 extern void device_add_disk(struct device *parent, struct gendisk *disk,
 			    const struct attribute_group **groups);
 static inline void add_disk(struct gendisk *disk)