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-rw-r--r--Documentation/admin-guide/iostats.rst5
-rw-r--r--block/bio.c8
-rw-r--r--block/blk-core.c4
-rw-r--r--include/linux/genhd.h2
4 files changed, 11 insertions, 8 deletions
diff --git a/Documentation/admin-guide/iostats.rst b/Documentation/admin-guide/iostats.rst
index df5b8345c41d..9b14b0c2c9c4 100644
--- a/Documentation/admin-guide/iostats.rst
+++ b/Documentation/admin-guide/iostats.rst
@@ -100,7 +100,7 @@ Field 10 -- # of milliseconds spent doing I/Os (unsigned int)
Since 5.0 this field counts jiffies when at least one request was
started or completed. If request runs more than 2 jiffies then some
- I/O time will not be accounted unless there are other requests.
+ I/O time might be not accounted in case of concurrent requests.
Field 11 -- weighted # of milliseconds spent doing I/Os (unsigned int)
This field is incremented at each I/O start, I/O completion, I/O
@@ -143,6 +143,9 @@ are summed (possibly overflowing the unsigned long variable they are
summed to) and the result given to the user. There is no convenient
user interface for accessing the per-CPU counters themselves.
+Since 4.19 request times are measured with nanoseconds precision and
+truncated to milliseconds before showing in this interface.
+
Disks vs Partitions
-------------------
diff --git a/block/bio.c b/block/bio.c
index 209715765a7a..68f65ef2ceba 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1768,14 +1768,14 @@ defer:
schedule_work(&bio_dirty_work);
}
-void update_io_ticks(struct hd_struct *part, unsigned long now)
+void update_io_ticks(struct hd_struct *part, unsigned long now, bool end)
{
unsigned long stamp;
again:
stamp = READ_ONCE(part->stamp);
if (unlikely(stamp != now)) {
if (likely(cmpxchg(&part->stamp, stamp, now) == stamp)) {
- __part_stat_add(part, io_ticks, 1);
+ __part_stat_add(part, io_ticks, end ? now - stamp : 1);
}
}
if (part->partno) {
@@ -1791,7 +1791,7 @@ void generic_start_io_acct(struct request_queue *q, int op,
part_stat_lock();
- update_io_ticks(part, jiffies);
+ update_io_ticks(part, jiffies, false);
part_stat_inc(part, ios[sgrp]);
part_stat_add(part, sectors[sgrp], sectors);
part_inc_in_flight(q, part, op_is_write(op));
@@ -1809,7 +1809,7 @@ void generic_end_io_acct(struct request_queue *q, int req_op,
part_stat_lock();
- update_io_ticks(part, now);
+ update_io_ticks(part, now, true);
part_stat_add(part, nsecs[sgrp], jiffies_to_nsecs(duration));
part_stat_add(part, time_in_queue, duration);
part_dec_in_flight(q, part, op_is_write(req_op));
diff --git a/block/blk-core.c b/block/blk-core.c
index abfdcf81a228..4401b30a1751 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1337,7 +1337,7 @@ void blk_account_io_done(struct request *req, u64 now)
part_stat_lock();
part = req->part;
- update_io_ticks(part, jiffies);
+ update_io_ticks(part, jiffies, true);
part_stat_inc(part, ios[sgrp]);
part_stat_add(part, nsecs[sgrp], now - req->start_time_ns);
part_stat_add(part, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns));
@@ -1379,7 +1379,7 @@ void blk_account_io_start(struct request *rq, bool new_io)
rq->part = part;
}
- update_io_ticks(part, jiffies);
+ update_io_ticks(part, jiffies, false);
part_stat_unlock();
}
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index da62b44b15be..13bb51f37b3f 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -422,7 +422,7 @@ void part_dec_in_flight(struct request_queue *q, struct hd_struct *part,
void part_inc_in_flight(struct request_queue *q, struct hd_struct *part,
int rw);
-void update_io_ticks(struct hd_struct *part, unsigned long now);
+void update_io_ticks(struct hd_struct *part, unsigned long now, bool end);
/* block/genhd.c */
extern void device_add_disk(struct device *parent, struct gendisk *disk,