The tg_may_dispatch() will call tg_with_in_bps_limit() and
tg_with_in_iops_limit() to check if we can dispatch a bio or
not, which will calculate bps/iops limitation multiple times.
But tg_may_dispatch() is always called under queue lock, which
means the bps/iops limitation will not change in tg_may_dispatch().
So we can calculate the bps/iops limitation only once, and pass
them to tg_with_in_bps_limit() and tg_with_in_iops_limit() to
avoid calculating bps/iops limitation repeatedly.
Signed-off-by: Baolin Wang <baolin.w...@linux.alibaba.com>
---
block/blk-throttle.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index ca9002d..8719e37 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -894,7 +894,7 @@ static inline void throtl_trim_slice(struct throtl_grp *tg,
bool rw)
}
static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
- unsigned long *wait)
+ u32 iops_limit, unsigned long *wait)
{
bool rw = bio_data_dir(bio);
unsigned int io_allowed;
@@ -913,7 +913,7 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg,
struct bio *bio,
* have been trimmed.
*/
- tmp = (u64)tg_iops_limit(tg, rw) * jiffy_elapsed_rnd;
+ tmp = (u64)iops_limit * jiffy_elapsed_rnd;
do_div(tmp, HZ);
if (tmp > UINT_MAX)
@@ -936,7 +936,7 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg,
struct bio *bio,
}
static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
- unsigned long *wait)
+ u64 bps_limit, unsigned long *wait)
{
bool rw = bio_data_dir(bio);
u64 bytes_allowed, extra_bytes, tmp;
@@ -951,7 +951,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg,
struct bio *bio,
jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice);
- tmp = tg_bps_limit(tg, rw) * jiffy_elapsed_rnd;
+ tmp = bps_limit * jiffy_elapsed_rnd;
do_div(tmp, HZ);
bytes_allowed = tmp;
@@ -963,7 +963,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg,
struct bio *bio,
/* Calc approx time to dispatch */
extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed;
- jiffy_wait = div64_u64(extra_bytes * HZ, tg_bps_limit(tg, rw));
+ jiffy_wait = div64_u64(extra_bytes * HZ, bps_limit);
if (!jiffy_wait)
jiffy_wait = 1;
@@ -987,6 +987,8 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct
bio *bio,
{
bool rw = bio_data_dir(bio);
unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
+ u64 bps_limit = tg_bps_limit(tg, rw);
+ u32 iops_limit = tg_iops_limit(tg, rw);
/*
* Currently whole state machine of group depends on first bio
@@ -998,8 +1000,7 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct
bio *bio,
bio != throtl_peek_queued(&tg->service_queue.queued[rw]));
/* If tg->bps = -1, then BW is unlimited */
- if (tg_bps_limit(tg, rw) == U64_MAX &&
- tg_iops_limit(tg, rw) == UINT_MAX) {
+ if (bps_limit == U64_MAX && iops_limit == UINT_MAX) {
if (wait)
*wait = 0;
return true;
@@ -1021,8 +1022,8 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct
bio *bio,
jiffies + tg->td->throtl_slice);
}
- if (tg_with_in_bps_limit(tg, bio, &bps_wait) &&
- tg_with_in_iops_limit(tg, bio, &iops_wait)) {
+ if (tg_with_in_bps_limit(tg, bio, bps_limit, &bps_wait) &&
+ tg_with_in_iops_limit(tg, bio, iops_limit, &iops_wait)) {
if (wait)
*wait = 0;
return true;
--
1.8.3.1
