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| author | Tejun Heo <tj@kernel.org> | 2013-05-14 13:52:38 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-05-14 13:52:38 -0700 |
| commit | 9e660acffcd1b5adc4ec1ffba0cbb584f86b8907 (patch) | |
| tree | 96ac75e374c9a7069e07093a1c636aebf76d8a3d /block/blk-throttle.c | |
| parent | 2a12f0dcdad1ba7c0e53bbff8e5f6d0ee7a29882 (diff) | |
| download | lwn-9e660acffcd1b5adc4ec1ffba0cbb584f86b8907.tar.gz lwn-9e660acffcd1b5adc4ec1ffba0cbb584f86b8907.zip | |
blk-throttle: make blk_throtl_bio() ready for hierarchy
Currently, blk_throtl_bio() issues the passed in bio directly if it's
within limits of its associated tg (throtl_grp). This behavior
becomes incorrect with hierarchy support as the bio should be
accounted to and throttled by the ancestor throtl_grps too.
This patch makes the direct issue path of blk_throtl_bio() to loop
until it reaches the top-level service_queue or gets throttled. If
the former, the bio can be issued directly; otherwise, it gets queued
at the first layer it was above limits.
As tg->parent_sq is always the top-level service queue currently, this
patch in itself doesn't make any behavior differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Diffstat (limited to 'block/blk-throttle.c')
| -rw-r--r-- | block/blk-throttle.c | 27 |
1 files changed, 20 insertions, 7 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 8c6e13359781..52321a42cd78 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1239,12 +1239,16 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio) sq = &tg->service_queue; - /* throtl is FIFO - if other bios are already queued, should queue */ - if (sq->nr_queued[rw]) - goto queue_bio; + while (true) { + /* throtl is FIFO - if bios are already queued, should queue */ + if (sq->nr_queued[rw]) + break; - /* Bio is with-in rate limit of group */ - if (tg_may_dispatch(tg, bio, NULL)) { + /* if above limits, break to queue */ + if (!tg_may_dispatch(tg, bio, NULL)) + break; + + /* within limits, let's charge and dispatch directly */ throtl_charge_bio(tg, bio); /* @@ -1259,10 +1263,19 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio) * So keep on trimming slice even if bio is not queued. */ throtl_trim_slice(tg, rw); - goto out_unlock; + + /* + * @bio passed through this layer without being throttled. + * Climb up the ladder. If we''re already at the top, it + * can be executed directly. + */ + sq = sq->parent_sq; + tg = sq_to_tg(sq); + if (!tg) + goto out_unlock; } -queue_bio: + /* out-of-limit, queue to @tg */ throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d", rw == READ ? 'R' : 'W', tg->bytes_disp[rw], bio->bi_size, tg->bps[rw], |