[PATCH 2/2] blk-throttle: improve bypassing bios checkings

From: Yu Kuai
Date: Wed Sep 21 2022 - 05:42:38 EST


From: Yu Kuai <yukuai3@xxxxxxxxxx>

"tg->has_rules" is extended to "tg->has_rules_iops/bps", thus bios that
don't need to be throttled can be checked accurately.

With this patch, bio will be throttled if:

1) Bio is read/write, and corresponding read/write iops limit exist.
2) If corresponding doesn't exist, corresponding bps limit exist and
bio is not throttled before.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
block/blk-throttle.c | 13 +++++++++----
block/blk-throttle.h | 22 +++++++++++++++++++---
2 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index a062539d84d0..78316955e30f 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -421,11 +421,16 @@ static void tg_update_has_rules(struct throtl_grp *tg)
struct throtl_data *td = tg->td;
int rw;

- for (rw = READ; rw <= WRITE; rw++)
- tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) ||
+ for (rw = READ; rw <= WRITE; rw++) {
+ tg->has_rules_iops[rw] =
+ (parent_tg && parent_tg->has_rules_iops[rw]) ||
(td->limit_valid[td->limit_index] &&
- (tg_bps_limit(tg, rw) != U64_MAX ||
- tg_iops_limit(tg, rw) != UINT_MAX));
+ tg_iops_limit(tg, rw) != UINT_MAX);
+ tg->has_rules_bps[rw] =
+ (parent_tg && parent_tg->has_rules_bps[rw]) ||
+ (td->limit_valid[td->limit_index] &&
+ (tg_bps_limit(tg, rw) != U64_MAX));
+ }
}

static void throtl_pd_online(struct blkg_policy_data *pd)
diff --git a/block/blk-throttle.h b/block/blk-throttle.h
index 3994b89dfa11..69f00012d616 100644
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -98,7 +98,8 @@ struct throtl_grp {
unsigned int flags;

/* are there any throtl rules between this group and td? */
- bool has_rules[2];
+ bool has_rules_bps[2];
+ bool has_rules_iops[2];

/* internally used bytes per second rate limits */
uint64_t bps[2][LIMIT_CNT];
@@ -178,11 +179,26 @@ void blk_throtl_exit(struct request_queue *q);
void blk_throtl_register_queue(struct request_queue *q);
bool __blk_throtl_bio(struct bio *bio);
void blk_throtl_cancel_bios(struct request_queue *q);
-static inline bool blk_throtl_bio(struct bio *bio)
+
+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);
+
+ /* iops limit is always counted */
+ if (tg->has_rules_iops[rw])
+ return true;
+
+ if (tg->has_rules_bps[rw] && !bio_flagged(bio, BIO_BPS_THROTTLED))
+ return true;
+
+ return false;
+}
+
+static inline bool blk_throtl_bio(struct bio *bio)
+{

- if (!tg->has_rules[bio_data_dir(bio)])
+ if (!blk_should_throtl(bio))
return false;

return __blk_throtl_bio(bio);
--
2.31.1