From ffa772cfe9356ce94d3061335c2681f60e7c1c5b Mon Sep 17 00:00:00 2001 From: Yang Yang Date: Fri, 5 Feb 2021 01:13:10 -0800 Subject: kyber: introduce kyber_depth_updated() Hang occurs when user changes the scheduler queue depth, by writing to the 'nr_requests' sysfs file of that device. The details of the environment that we found the problem are as follows: an eMMC block device total driver tags: 16 default queue_depth: 32 kqd->async_depth initialized in kyber_init_sched() with queue_depth=32 Then we change queue_depth to 256, by writing to the 'nr_requests' sysfs file. But kqd->async_depth don't be updated after queue_depth changes. Now the value of async depth is too small for queue_depth=256, this may cause hang. This patch introduces kyber_depth_updated(), so that kyber can update async depth when queue depth changes. Signed-off-by: Yang Yang Reviewed-by: Omar Sandoval Signed-off-by: Jens Axboe --- block/kyber-iosched.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) (limited to 'block') diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c index f13da10953bf..33d34d69cade 100644 --- a/block/kyber-iosched.c +++ b/block/kyber-iosched.c @@ -355,19 +355,9 @@ static void kyber_timer_fn(struct timer_list *t) } } -static unsigned int kyber_sched_tags_shift(struct request_queue *q) -{ - /* - * All of the hardware queues have the same depth, so we can just grab - * the shift of the first one. - */ - return q->queue_hw_ctx[0]->sched_tags->bitmap_tags->sb.shift; -} - static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q) { struct kyber_queue_data *kqd; - unsigned int shift; int ret = -ENOMEM; int i; @@ -402,9 +392,6 @@ static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q) kqd->latency_targets[i] = kyber_latency_targets[i]; } - shift = kyber_sched_tags_shift(q); - kqd->async_depth = (1U << shift) * KYBER_ASYNC_PERCENT / 100U; - return kqd; err_buckets: @@ -460,9 +447,19 @@ static void kyber_ctx_queue_init(struct kyber_ctx_queue *kcq) INIT_LIST_HEAD(&kcq->rq_list[i]); } -static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx) +static void kyber_depth_updated(struct blk_mq_hw_ctx *hctx) { struct kyber_queue_data *kqd = hctx->queue->elevator->elevator_data; + struct blk_mq_tags *tags = hctx->sched_tags; + unsigned int shift = tags->bitmap_tags->sb.shift; + + kqd->async_depth = (1U << shift) * KYBER_ASYNC_PERCENT / 100U; + + sbitmap_queue_min_shallow_depth(tags->bitmap_tags, kqd->async_depth); +} + +static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx) +{ struct kyber_hctx_data *khd; int i; @@ -504,8 +501,7 @@ static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx) khd->batching = 0; hctx->sched_data = khd; - sbitmap_queue_min_shallow_depth(hctx->sched_tags->bitmap_tags, - kqd->async_depth); + kyber_depth_updated(hctx); return 0; @@ -1024,6 +1020,7 @@ static struct elevator_type kyber_sched = { .completed_request = kyber_completed_request, .dispatch_request = kyber_dispatch_request, .has_work = kyber_has_work, + .depth_updated = kyber_depth_updated, }, #ifdef CONFIG_BLK_DEBUG_FS .queue_debugfs_attrs = kyber_queue_debugfs_attrs, -- cgit v1.2.3-59-g8ed1b