Re: [PATCH -next RFC] block: count 'ios' and 'sectors' when io is done for bio-based device
From: Yu Kuai
Date: Tue Mar 07 2023 - 05:45:40 EST
Hi,
在 2023/02/28 9:01, Yu Kuai 写道:
Hi,
friendly ping ...
Thanks,
Kuai
在 2023/02/23 17:12, Yu Kuai 写道:
From: Yu Kuai <yukuai3@xxxxxxxxxx>
While using iostat for raid, I observed very strange 'await'
occasionally, and turns out it's due to that 'ios' and 'sectors' is
counted in bdev_start_io_acct(), while 'nsecs' is counted in
bdev_end_io_acct(). I'm not sure why they are ccounted like that
but I think this behaviour is obviously wrong because user will get
wrong disk stats.
Fix the problem by counting 'ios' and 'sectors' when io is done, like
what rq-based device does.
Can anyone help to review this change? Or is there any reason to count
'ios' and 'sectors' when io is started?
Thanks,
Kuai
Fixes: 394ffa503bc4 ("blk: introduce generic io stat accounting help
function")
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
block/blk-core.c | 16 ++++++----------
drivers/md/dm.c | 6 +++---
drivers/nvme/host/multipath.c | 8 ++++----
include/linux/blkdev.h | 5 ++---
4 files changed, 15 insertions(+), 20 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 82b5b2c53f1e..fe1d320f5f07 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -953,16 +953,11 @@ void update_io_ticks(struct block_device *part,
unsigned long now, bool end)
}
}
-unsigned long bdev_start_io_acct(struct block_device *bdev,
- unsigned int sectors, enum req_op op,
+unsigned long bdev_start_io_acct(struct block_device *bdev, enum
req_op op,
unsigned long start_time)
{
- const int sgrp = op_stat_group(op);
-
part_stat_lock();
update_io_ticks(bdev, start_time, false);
- part_stat_inc(bdev, ios[sgrp]);
- part_stat_add(bdev, sectors[sgrp], sectors);
part_stat_local_inc(bdev, in_flight[op_is_write(op)]);
part_stat_unlock();
@@ -978,13 +973,12 @@ EXPORT_SYMBOL(bdev_start_io_acct);
*/
unsigned long bio_start_io_acct(struct bio *bio)
{
- return bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio),
- bio_op(bio), jiffies);
+ return bdev_start_io_acct(bio->bi_bdev, bio_op(bio), jiffies);
}
EXPORT_SYMBOL_GPL(bio_start_io_acct);
void bdev_end_io_acct(struct block_device *bdev, enum req_op op,
- unsigned long start_time)
+ unsigned int sectors, unsigned long start_time)
{
const int sgrp = op_stat_group(op);
unsigned long now = READ_ONCE(jiffies);
@@ -992,6 +986,8 @@ void bdev_end_io_acct(struct block_device *bdev,
enum req_op op,
part_stat_lock();
update_io_ticks(bdev, now, true);
+ part_stat_inc(bdev, ios[sgrp]);
+ part_stat_add(bdev, sectors[sgrp], sectors);
part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration));
part_stat_local_dec(bdev, in_flight[op_is_write(op)]);
part_stat_unlock();
@@ -1001,7 +997,7 @@ EXPORT_SYMBOL(bdev_end_io_acct);
void bio_end_io_acct_remapped(struct bio *bio, unsigned long
start_time,
struct block_device *orig_bdev)
{
- bdev_end_io_acct(orig_bdev, bio_op(bio), start_time);
+ bdev_end_io_acct(orig_bdev, bio_op(bio), bio_sectors(bio),
start_time);
}
EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index eace45a18d45..f5cc330bb549 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -512,10 +512,10 @@ static void dm_io_acct(struct dm_io *io, bool end)
sectors = io->sectors;
if (!end)
- bdev_start_io_acct(bio->bi_bdev, sectors, bio_op(bio),
- start_time);
+ bdev_start_io_acct(bio->bi_bdev, bio_op(bio), start_time);
else
- bdev_end_io_acct(bio->bi_bdev, bio_op(bio), start_time);
+ bdev_end_io_acct(bio->bi_bdev, bio_op(bio), sectors,
+ start_time);
if (static_branch_unlikely(&stats_enabled) &&
unlikely(dm_stats_used(&md->stats))) {
diff --git a/drivers/nvme/host/multipath.c
b/drivers/nvme/host/multipath.c
index fc39d01e7b63..9171452e2f6d 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -123,9 +123,8 @@ void nvme_mpath_start_request(struct request *rq)
return;
nvme_req(rq)->flags |= NVME_MPATH_IO_STATS;
- nvme_req(rq)->start_time = bdev_start_io_acct(disk->part0,
- blk_rq_bytes(rq) >> SECTOR_SHIFT,
- req_op(rq), jiffies);
+ nvme_req(rq)->start_time = bdev_start_io_acct(disk->part0,
req_op(rq),
+ jiffies);
}
EXPORT_SYMBOL_GPL(nvme_mpath_start_request);
@@ -136,7 +135,8 @@ void nvme_mpath_end_request(struct request *rq)
if (!(nvme_req(rq)->flags & NVME_MPATH_IO_STATS))
return;
bdev_end_io_acct(ns->head->disk->part0, req_op(rq),
- nvme_req(rq)->start_time);
+ blk_rq_bytes(rq) >> SECTOR_SHIFT,
+ nvme_req(rq)->start_time);
}
void nvme_kick_requeue_lists(struct nvme_ctrl *ctrl)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d1aee08f8c18..941304f17492 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1446,11 +1446,10 @@ static inline void blk_wake_io_task(struct
task_struct *waiter)
wake_up_process(waiter);
}
-unsigned long bdev_start_io_acct(struct block_device *bdev,
- unsigned int sectors, enum req_op op,
+unsigned long bdev_start_io_acct(struct block_device *bdev, enum
req_op op,
unsigned long start_time);
void bdev_end_io_acct(struct block_device *bdev, enum req_op op,
- unsigned long start_time);
+ unsigned int sectors, unsigned long start_time);
unsigned long bio_start_io_acct(struct bio *bio);
void bio_end_io_acct_remapped(struct bio *bio, unsigned long
start_time,
.