Re: [PATCH] queue stall with blk-mq-sched
From: Jens Axboe <axboe@kernel.dk>
Date: 2017-01-24 22:06:53
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
On 01/24/2017 12:55 PM, Jens Axboe wrote:
Try this patch. We only want to bump it for the driver tags, not the scheduler side.
More complete version, this one actually tested. I think this should fix your issue, let me know.
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index a49ec77..1b156ca 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c@@ -90,9 +90,11 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, return atomic_read(&hctx->nr_active) < depth; } -static int __blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt) +static int __blk_mq_get_tag(struct blk_mq_alloc_data *data, + struct sbitmap_queue *bt) { - if (!hctx_may_queue(hctx, bt)) + if (!(data->flags & BLK_MQ_REQ_INTERNAL) && + !hctx_may_queue(data->hctx, bt)) return -1; return __sbitmap_queue_get(bt); }
@@ -118,7 +120,7 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) tag_offset = tags->nr_reserved_tags; } - tag = __blk_mq_get_tag(data->hctx, bt); + tag = __blk_mq_get_tag(data, bt); if (tag != -1) goto found_tag;
@@ -129,7 +131,7 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) do { prepare_to_wait(&ws->wait, &wait, TASK_UNINTERRUPTIBLE); - tag = __blk_mq_get_tag(data->hctx, bt); + tag = __blk_mq_get_tag(data, bt); if (tag != -1) break;
@@ -144,7 +146,7 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) * Retry tag allocation after running the hardware queue, * as running the queue may also have found completions. */ - tag = __blk_mq_get_tag(data->hctx, bt); + tag = __blk_mq_get_tag(data, bt); if (tag != -1) break;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index ee69e5e..dcb5676 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c@@ -230,15 +230,14 @@ struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data, rq = tags->static_rqs[tag]; - if (blk_mq_tag_busy(data->hctx)) { - rq->rq_flags = RQF_MQ_INFLIGHT; - atomic_inc(&data->hctx->nr_active); - } - if (data->flags & BLK_MQ_REQ_INTERNAL) { rq->tag = -1; rq->internal_tag = tag; } else { + if (blk_mq_tag_busy(data->hctx)) { + rq->rq_flags = RQF_MQ_INFLIGHT; + atomic_inc(&data->hctx->nr_active); + } rq->tag = tag; rq->internal_tag = -1; }
@@ -869,6 +868,10 @@ static bool blk_mq_get_driver_tag(struct request *rq, rq->tag = blk_mq_get_tag(&data); if (rq->tag >= 0) { + if (blk_mq_tag_busy(data.hctx)) { + rq->rq_flags |= RQF_MQ_INFLIGHT; + atomic_inc(&data.hctx->nr_active); + } data.hctx->tags->rqs[rq->tag] = rq; goto done; }
--
Jens Axboe