blk-iolatency: use q->nr_requests directly (ff4cee08) · Commits · 戴 / test

We were using blk_queue_depth() assuming that it would return nr_requests, but we hit a case in production on drives that had to have NCQ turned off in order for them to not shit the bed which resulted in a qd of 1, even though the nr_requests was much larger. iolatency really only cares about requests we are allowed to queue up, as any io that get's onto the request list is going to be serviced soonish, so we want to be throttling before the bio gets onto the request list. To make iolatency work as expected, simply use q->nr_requests instead of blk_queue_depth() as that is what we actually care about. Signed-off-by:

Josef Bacik <josef@toxicpanda.com> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/blk-iolatency.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -255,7 +255,7 @@ static void scale_cookie_change(struct blk_iolatency *blkiolat,
		struct child_latency_info *lat_info,
		bool up)
		{
		unsigned long qd = blk_queue_depth(blkiolat->rqos.q);
		unsigned long qd = blkiolat->rqos.q->nr_requests;
		unsigned long scale = scale_amount(qd, up);
		unsigned long old = atomic_read(&lat_info->scale_cookie);
		unsigned long max_scale = qd << 1;
		@@ -295,7 +295,7 @@ static void scale_cookie_change(struct blk_iolatency *blkiolat,
		*/
		static void scale_change(struct iolatency_grp *iolat, bool up)
		{
		unsigned long qd = blk_queue_depth(iolat->blkiolat->rqos.q);
		unsigned long qd = iolat->blkiolat->rqos.q->nr_requests;
		unsigned long scale = scale_amount(qd, up);
		unsigned long old = iolat->rq_depth.max_depth;

		@@ -857,7 +857,7 @@ static void iolatency_pd_init(struct blkg_policy_data *pd)

		rq_wait_init(&iolat->rq_wait);
		spin_lock_init(&iolat->child_lat.lock);
		iolat->rq_depth.queue_depth = blk_queue_depth(blkg->q);
		iolat->rq_depth.queue_depth = blkg->q->nr_requests;
		iolat->rq_depth.max_depth = UINT_MAX;
		iolat->rq_depth.default_depth = iolat->rq_depth.queue_depth;
		iolat->blkiolat = blkiolat;

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