Hi
Sorry for delay（Chinese Labor Day holiday).
在 2023/4/29 上午3:05, Andrea Righi 写道:
On Sat, Apr 01, 2023 at 05:47:08PM +0800, Jinke Han wrote:
From: Jinke Han <hanjinke.666@xxxxxxxxxxxxx>
After commit f382fb0bcef4 ("block: remove legacy IO schedulers"),
blkio.throttle.io_serviced and blkio.throttle.io_service_bytes become
the only stable io stats interface of cgroup v1, and these statistics
are done in the blk-throttle code. But the current code only counts the
bios that are actually throttled. When the user does not add the throttle
limit, the io stats for cgroup v1 has nothing. I fix it according to the
statistical method of v2, and made it count all ios accurately.
Fixes: a7b36ee6ba29 ("block: move blk-throtl fast path inline")
Signed-off-by: Jinke Han <hanjinke.666@xxxxxxxxxxxxx>
Thanks for fixing this!
The code looks correct to me, but this seems to report io statistics
only if at least one throttling limit is defined. IIRC with cgroup v1 it
was possible to see the io statistics inside a cgroup also with no
throttling limits configured.
Basically to restore the old behavior we would need to drop the
cgroup_subsys_on_dfl() check, something like the following (on top of
your patch).
But I'm not sure if we're breaking other behaviors in this way...
opinions?
block/blk-cgroup.c | 3 ---
block/blk-throttle.h | 12 +++++-------
2 files changed, 5 insertions(+), 10 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 79138bfc6001..43af86db7cf3 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -2045,9 +2045,6 @@ 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.h b/block/blk-throttle.h
index d1ccbfe9f797..bcb40ee2eeba 100644
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -185,14 +185,12 @@ 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);
+ 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);
It seems that statistics have been carried out in both v1 and v2，we can
get the statistics of v2 from io.stat, is it necessary to count v2 here?
