From: Jeff Mahoney <jeffm@xxxxxxxx>
The i/o accounting published in /proc/diskstats for mdraid is currently
broken. md_make_request does the accounting for every bio passed but
when a bio needs to be split, all the split bios are also submitted
through md_make_request, resulting in multiple accounting.
As a result, a quick test on a RAID6 volume displayed the following
behavior:
131072+0 records in
131072+0 records out
67108864 bytes (67 MB, 64 MiB) copied, 13.9227 s, 4.8 MB/s
... shows 131072 sectors read -- 64 MiB. Correct.
512+0 records in
512+0 records out
67108864 bytes (67 MB, 64 MiB) copied, 0.287365 s, 234 MB/s
... shows 196608 sectors read -- 96 MiB. With a 64k stripe size, we're
seeing some splitting.
512+0 records in
512+0 records out
536870912 bytes (537 MB, 512 MiB) copied, 0.705004 s, 762 MB/s
... shows 4718624 sectors read -- 2.25 GiB transferred. Lots of splitting
and a stats explosion.
The fix is to push the accounting into the personality make_request
callbacks so that only the bios actually submitted for I/O will be
accounted.
Signed-off-by: Jeff Mahoney <jeffm@xxxxxxxx>
---
drivers/md/md-faulty.c | 1 +
drivers/md/md-linear.c | 1 +
drivers/md/md-multipath.c | 1 +
drivers/md/md.c | 21 +++++++++++++++------
drivers/md/md.h | 1 +
drivers/md/raid0.c | 1 +
drivers/md/raid1.c | 3 +++
drivers/md/raid10.c | 3 +++
drivers/md/raid5.c | 3 +++
9 files changed, 29 insertions(+), 6 deletions(-)
diff --git a/drivers/md/md-faulty.c b/drivers/md/md-faulty.c
index 50ad4ba86f0e..25e2c72ef920 100644
--- a/drivers/md/md-faulty.c
+++ b/drivers/md/md-faulty.c
@@ -214,6 +214,7 @@ static bool faulty_make_request(struct mddev *mddev, struct bio *bio)
} else
bio_set_dev(bio, conf->rdev->bdev);
+ md_io_acct(mddev, bio_op(bio), bio_sectors(bio));
generic_make_request(bio);
return true;
}
diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
index 26c75c0199fa..ec0dbc0f1d76 100644
--- a/drivers/md/md-linear.c
+++ b/drivers/md/md-linear.c
@@ -271,6 +271,7 @@ static bool linear_make_request(struct mddev *mddev, struct bio *bio)
bio = split;
}
+ md_io_acct(mddev, bio_op(bio), bio_sectors(bio));
bio_set_dev(bio, tmp_dev->rdev->bdev);
bio->bi_iter.bi_sector = bio->bi_iter.bi_sector -
start_sector + data_offset;
diff --git a/drivers/md/md-multipath.c b/drivers/md/md-multipath.c
index 152f9e65a226..c3afe3f62a88 100644
--- a/drivers/md/md-multipath.c
+++ b/drivers/md/md-multipath.c
@@ -131,6 +131,7 @@ static bool multipath_make_request(struct mddev *mddev, struct bio * bio)
mp_bh->bio.bi_private = mp_bh;
mddev_check_writesame(mddev, &mp_bh->bio);
mddev_check_write_zeroes(mddev, &mp_bh->bio);
+ md_io_acct(mddev, bio_op(bio), bio_sectors(bio));
generic_make_request(&mp_bh->bio);
return true;
}
diff --git a/drivers/md/md.c b/drivers/md/md.c
index f567f536b529..e8078a16419b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -463,10 +463,24 @@ void md_handle_request(struct mddev *mddev, struct bio *bio)
}
EXPORT_SYMBOL(md_handle_request);
+/*
+ * This is generic_start_io_acct without the inflight tracking. Since
+ * we can't reliably call generic_end_io_acct, the inflight counter
+ * would also be unreliable and it's better to keep it at 0.
+ */
+void md_io_acct(struct mddev *mddev, int sgrp, unsigned int sectors)
+{
+ part_stat_lock();
+ part_stat_inc(&mddev->gendisk->part0, ios[sgrp]);
+ part_stat_add(&mddev->gendisk->part0, sectors[sgrp], sectors);
+ part_stat_unlock();
+
+}
+EXPORT_SYMBOL_GPL(md_io_acct);
+
static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)
{
const int rw = bio_data_dir(bio);
- const int sgrp = op_stat_group(bio_op(bio));
struct mddev *mddev = bio->bi_disk->private_data;
unsigned int sectors;
@@ -498,11 +512,6 @@ static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)
md_handle_request(mddev, bio);
- part_stat_lock();
- part_stat_inc(&mddev->gendisk->part0, ios[sgrp]);
- part_stat_add(&mddev->gendisk->part0, sectors[sgrp], sectors);
- part_stat_unlock();
-
return BLK_QC_T_NONE;
}
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 612814d07d35..5834427f7557 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -741,6 +741,7 @@ extern void mddev_suspend(struct mddev *mddev);
extern void mddev_resume(struct mddev *mddev);
extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
struct mddev *mddev);
+extern void md_io_acct(struct mddev *mddev, int sgrp, unsigned int sectors);
extern void md_reload_sb(struct mddev *mddev, int raid_disk);
extern void md_update_sb(struct mddev *mddev, int force);
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 322386ff5d22..ac1109d1d48d 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -633,6 +633,7 @@ static bool raid0_make_request(struct mddev *mddev, struct bio *bio)
disk_devt(mddev->gendisk), bio_sector);
mddev_check_writesame(mddev, bio);
mddev_check_write_zeroes(mddev, bio);
+ md_io_acct(mddev, bio_op(bio), bio_sectors(bio));
generic_make_request(bio);
return true;
}
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index dcd27f3da84e..f0d620e2b90f 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1318,6 +1318,7 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
r1_bio->sectors = max_sectors;
}
+ md_io_acct(mddev, bio_op(bio), bio_sectors(bio));
r1_bio->read_disk = rdisk;
read_bio = bio_clone_fast(bio, gfp, &mddev->bio_set);
@@ -1489,6 +1490,8 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
r1_bio->sectors = max_sectors;
}
+ md_io_acct(mddev, bio_op(bio), bio_sectors(bio));
+
atomic_set(&r1_bio->remaining, 1);
atomic_set(&r1_bio->behind_remaining, 0);
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index ec136e44aef7..b8e8d7f67f65 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1202,6 +1202,8 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
}
slot = r10_bio->read_slot;
+ md_io_acct(mddev, bio_op(bio), bio_sectors(bio));
+
read_bio = bio_clone_fast(bio, gfp, &mddev->bio_set);
r10_bio->devs[slot].bio = read_bio;
@@ -1485,6 +1487,7 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
r10_bio->master_bio = bio;
}
+ md_io_acct(mddev, bio_op(bio), bio_sectors(bio));
atomic_set(&r10_bio->remaining, 1);
md_bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index ab8067f9ce8c..e57109e39fcd 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5316,6 +5316,7 @@ static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
if (!raid5_read_one_chunk(mddev, raid_bio))
return raid_bio;
+ md_io_acct(mddev, bio_op(raid_bio), bio_sectors(raid_bio));
return NULL;
}
@@ -5634,6 +5635,8 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
last_sector = bio_end_sector(bi);
bi->bi_next = NULL;
+ md_io_acct(mddev, bio_op(bi), bio_sectors(bi));
+
prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
int previous;
--
2.16.4
