2023-03-28 14:25:11

by hanjinke

[permalink] [raw]
Subject: [PATCH] blk-throttle: Fix io statistics for cgroup v1

From: Jinke Han <[email protected]>

Now the io statistics of cgroup v1 are no longer accurate. Although
in the long run it's best that rstat is a good implementation of
cgroup v1 io statistics. But before that, we'd better fix this issue.

Signed-off-by: Jinke Han <[email protected]>
---
block/blk-cgroup.c | 3 +++
block/blk-throttle.c | 6 ------
block/blk-throttle.h | 9 +++++++++
3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index bd50b55bdb61..677e4473e45e 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -2033,6 +2033,9 @@ void blk_cgroup_bio_start(struct bio *bio)
struct blkg_iostat_set *bis;
unsigned long flags;

+ if (!cgroup_subsys_on_dfl(io_cgrp_subsys))
+ return;
+
/* Root-level stats are sourced from system-wide IO stats */
if (!cgroup_parent(blkcg->css.cgroup))
return;
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 47e9d8be68f3..2be66e9430f7 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2174,12 +2174,6 @@ bool __blk_throtl_bio(struct bio *bio)

rcu_read_lock();

- if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) {
- blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf,
- bio->bi_iter.bi_size);
- blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1);
- }
-
spin_lock_irq(&q->queue_lock);

throtl_update_latency_buckets(td);
diff --git a/block/blk-throttle.h b/block/blk-throttle.h
index ef4b7a4de987..d1ccbfe9f797 100644
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -185,6 +185,15 @@ static inline bool blk_should_throtl(struct bio *bio)
struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg);
int rw = bio_data_dir(bio);

+ if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) {
+ if (!bio_flagged(bio, BIO_CGROUP_ACCT)) {
+ bio_set_flag(bio, BIO_CGROUP_ACCT);
+ blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf,
+ bio->bi_iter.bi_size);
+ }
+ blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1);
+ }
+
/* iops limit is always counted */
if (tg->has_rules_iops[rw])
return true;
--
2.20.1