diff options
| author | Shaohua Li <shli@fb.com> | 2017-08-18 16:08:13 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2017-08-23 15:56:33 -0600 |
| commit | ea0ea2bc6dd8923d86a0fa98743dbeed98645486 (patch) | |
| tree | 462c57a8375b3c19d642d11dc43344a6f7aecab7 /block | |
| parent | 6470812e22261d2342ef1597be62e63a0423d691 (diff) | |
| download | lwn-ea0ea2bc6dd8923d86a0fa98743dbeed98645486.tar.gz lwn-ea0ea2bc6dd8923d86a0fa98743dbeed98645486.zip | |
blk-throttle: cap discard request size
discard request usually is very big and easily use all bandwidth budget
of a cgroup. discard request size doesn't really mean the size of data
written, so it doesn't make sense to account it into bandwidth budget.
Jens pointed out treating the size 0 doesn't make sense too, because
discard request does have cost. But it's not easy to find the actual
cost. This patch simply makes the size one sector.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-throttle.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index a7285bf2831c..80f5481fe9f6 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -382,6 +382,14 @@ static unsigned int tg_iops_limit(struct throtl_grp *tg, int rw) } \ } while (0) +static inline unsigned int throtl_bio_data_size(struct bio *bio) +{ + /* assume it's one sector */ + if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) + return 512; + return bio->bi_iter.bi_size; +} + static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg) { INIT_LIST_HEAD(&qn->node); @@ -934,6 +942,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, bool rw = bio_data_dir(bio); u64 bytes_allowed, extra_bytes, tmp; unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; + unsigned int bio_size = throtl_bio_data_size(bio); jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; @@ -947,14 +956,14 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, do_div(tmp, HZ); bytes_allowed = tmp; - if (tg->bytes_disp[rw] + bio->bi_iter.bi_size <= bytes_allowed) { + if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) { if (wait) *wait = 0; return true; } /* Calc approx time to dispatch */ - extra_bytes = tg->bytes_disp[rw] + bio->bi_iter.bi_size - bytes_allowed; + extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed; jiffy_wait = div64_u64(extra_bytes * HZ, tg_bps_limit(tg, rw)); if (!jiffy_wait) @@ -1034,11 +1043,12 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) { bool rw = bio_data_dir(bio); + unsigned int bio_size = throtl_bio_data_size(bio); /* Charge the bio to the group */ - tg->bytes_disp[rw] += bio->bi_iter.bi_size; + tg->bytes_disp[rw] += bio_size; tg->io_disp[rw]++; - tg->last_bytes_disp[rw] += bio->bi_iter.bi_size; + tg->last_bytes_disp[rw] += bio_size; tg->last_io_disp[rw]++; /* |