blk-throttle: make blk_throtl_bio() ready for hierarchy (9e660acf) · Commits · 戴 / test

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>

block/blk-throttle.c

+20 −7

Original line number	Diff line number	Diff line
		@@ -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 */
		while (true) {
		/* throtl is FIFO - if bios are already queued, should queue */
		if (sq->nr_queued[rw])
		goto queue_bio;
		break;

		/* if above limits, break to queue */
		if (!tg_may_dispatch(tg, bio, NULL))
		break;

		/* Bio is with-in rate limit of group */
		if (tg_may_dispatch(tg, bio, NULL)) {
		/* 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);

		/*
		* @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],

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