[PATCH RFC 5/5] block: add a statistic table for io sector

[Guoqing Jiang <guoqing.jiang@cloud.ionos.com>]

With the sector table, so we can know the distribution of
different IO size from upper layer, which means we could
have the opportunity to tune the performance based on the
mostly issued IOs.

Signed-off-by: Florian-Ewald Mueller <florian-ewald.mueller@cloud.ionos.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
---
 block/Kconfig             |  3 ++-
 block/blk-core.c          | 19 +++++++++++++++++++
 block/genhd.c             | 21 +++++++++++++++++++++
 include/linux/part_stat.h |  3 ++-
 4 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/block/Kconfig b/block/Kconfig
index dba71feaa85b..f1c4800969ef 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -179,7 +179,8 @@ config BLK_ADDITIONAL_DISKSTAT
 	bool "Block layer additional diskstat"
 	default n
 	help
-	Enabling this option adds io latency statistics for each block device.
+	Enabling this option adds io latency and io size statistics for each
+	block device.
 
 	If unsure, say N.
 
diff --git a/block/blk-core.c b/block/blk-core.c
index 7a129c8f1b23..d3c9f727926f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1436,12 +1436,29 @@ static void blk_additional_latency(struct hd_struct *part, const int sgrp,
 	part_stat_inc(part, latency_table[idx][sgrp]);
 
 }
+
+static void blk_additional_sector(struct hd_struct *part, const int sgrp,
+				  unsigned int sectors)
+{
+	unsigned int KB, idx;
+
+	KB = sectors / 2;
+	idx = (KB > 0) ? ilog2(KB) : 0;
+
+	idx = (idx > (ADD_STAT_NUM - 1)) ? (ADD_STAT_NUM - 1) : idx;
+	part_stat_inc(part, size_table[idx][sgrp]);
+}
 #else
 static void blk_additional_latency(struct hd_struct *part, const int sgrp,
 				   struct request *req, unsigned long start_jiffies)
 
 {
 }
+
+static void blk_additional_sector(struct hd_struct *part, const int sgrp,
+				  unsigned int sectors)
+{
+}
 #endif
 
 static void blk_account_io_completion(struct request *req, unsigned int bytes)
@@ -1452,6 +1469,7 @@ static void blk_account_io_completion(struct request *req, unsigned int bytes)
 
 		part_stat_lock();
 		part = req->part;
+		blk_additional_sector(part, sgrp, bytes >> SECTOR_SHIFT);
 		part_stat_add(part, sectors[sgrp], bytes >> 9);
 		part_stat_unlock();
 	}
@@ -1506,6 +1524,7 @@ unsigned long disk_start_io_acct(struct gendisk *disk, unsigned int sectors,
 	update_io_ticks(part, now, false);
 	part_stat_inc(part, ios[sgrp]);
 	part_stat_add(part, sectors[sgrp], sectors);
+	blk_additional_sector(part, sgrp, sectors);
 	part_stat_local_inc(part, in_flight[op_is_write(op)]);
 	part_stat_unlock();
 
diff --git a/block/genhd.c b/block/genhd.c
index a33937a74fb1..68e4735662f3 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1441,6 +1441,26 @@ static ssize_t io_latency_show(struct device *dev, struct device_attribute *attr
 
 static struct device_attribute dev_attr_io_latency =
 	__ATTR(io_latency, 0444, io_latency_show, NULL);
+
+static ssize_t io_size_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct hd_struct *p = dev_to_part(dev);
+	size_t count = 0;
+	int i, sgrp;
+
+	for (i = 0; i < ADD_STAT_NUM; i++) {
+		count += scnprintf(buf + count, PAGE_SIZE - count, "%5d KB: ", 1 << i);
+		for (sgrp = 0; sgrp < NR_STAT_GROUPS; sgrp++)
+			count += scnprintf(buf + count, PAGE_SIZE - count, "%lu ",
+					   part_stat_read(p, size_table[i][sgrp]));
+		count += scnprintf(buf + count, PAGE_SIZE - count, "\n");
+	}
+
+	return count;
+}
+
+static struct device_attribute dev_attr_io_size =
+	__ATTR(io_size, 0444, io_size_show, NULL);
 #endif
 
 static struct attribute *disk_attrs[] = {
@@ -1464,6 +1484,7 @@ static struct attribute *disk_attrs[] = {
 #endif
 #ifdef CONFIG_BLK_ADDITIONAL_DISKSTAT
 	&dev_attr_io_latency.attr,
+	&dev_attr_io_size.attr,
 #endif
 	NULL
 };
diff --git a/include/linux/part_stat.h b/include/linux/part_stat.h
index fe3def8c69d7..2b056cd70d1f 100644
--- a/include/linux/part_stat.h
+++ b/include/linux/part_stat.h
@@ -11,10 +11,11 @@ struct disk_stats {
 	unsigned long merges[NR_STAT_GROUPS];
 #ifdef CONFIG_BLK_ADDITIONAL_DISKSTAT
 /*
- * We measure latency (ms) for 1, 2, ..., 1024 and >=1024.
+ * We measure latency (ms) and size (sector) for 1, 2, ..., 1024 and >=1024.
  */
 #define ADD_STAT_NUM	12
 	unsigned long latency_table[ADD_STAT_NUM][NR_STAT_GROUPS];
+	unsigned long size_table[ADD_STAT_NUM][NR_STAT_GROUPS];
 #endif
 	unsigned long io_ticks;
 	local_t in_flight[2];
-- 
2.17.1