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Subject[PATCH 1/2] blk-throttle: remove THROTL_TG_HAS_IOPS_LIMIT
Date
From: Yu Kuai <yukuai3@huawei.com>

Currently, "tg->has_rules" and "tg->flags & THROTL_TG_HAS_IOPS_LIMIT"
both try to bypass bios that don't need to be throttled, however, they are
a little redundant and both not perfect:

1) "tg->has_rules" only distinguish read and write, but not iops and bps
limit.
2) "tg->flags & THROTL_TG_HAS_IOPS_LIMIT" only check if iops limit
exist, read and write is not distinguished, and bps limit is not
checked.

tg->has_rules will extended to distinguish bps and iops in the following
patch. There is no need to keep the flag.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
block/blk-throttle.c | 16 ++--------------
block/blk-throttle.h | 8 +-------
2 files changed, 3 insertions(+), 21 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 55f2d985cfbb..a062539d84d0 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -420,24 +420,12 @@ static void tg_update_has_rules(struct throtl_grp *tg)
struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq);
struct throtl_data *td = tg->td;
int rw;
- int has_iops_limit = 0;
-
- for (rw = READ; rw <= WRITE; rw++) {
- unsigned int iops_limit = tg_iops_limit(tg, rw);

+ for (rw = READ; rw <= WRITE; rw++)
tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) ||
(td->limit_valid[td->limit_index] &&
(tg_bps_limit(tg, rw) != U64_MAX ||
- iops_limit != UINT_MAX));
-
- if (iops_limit != UINT_MAX)
- has_iops_limit = 1;
- }
-
- if (has_iops_limit)
- tg->flags |= THROTL_TG_HAS_IOPS_LIMIT;
- else
- tg->flags &= ~THROTL_TG_HAS_IOPS_LIMIT;
+ tg_iops_limit(tg, rw) != UINT_MAX));
}

static void throtl_pd_online(struct blkg_policy_data *pd)
diff --git a/block/blk-throttle.h b/block/blk-throttle.h
index 66b4292b1b92..3994b89dfa11 100644
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -55,8 +55,7 @@ struct throtl_service_queue {
enum tg_state_flags {
THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */
THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */
- THROTL_TG_HAS_IOPS_LIMIT = 1 << 2, /* tg has iops limit */
- THROTL_TG_CANCELING = 1 << 3, /* starts to cancel bio */
+ THROTL_TG_CANCELING = 1 << 2, /* starts to cancel bio */
};

enum {
@@ -183,11 +182,6 @@ static inline bool blk_throtl_bio(struct bio *bio)
{
struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg);

- /* no need to throttle bps any more if the bio has been throttled */
- if (bio_flagged(bio, BIO_BPS_THROTTLED) &&
- !(tg->flags & THROTL_TG_HAS_IOPS_LIMIT))
- return false;
-
if (!tg->has_rules[bio_data_dir(bio)])
return false;

--
2.31.1
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