From f70ced09170761acb69840cafaace4abc72cba4b Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 25 Sep 2014 23:23:47 +0800 Subject: blk-mq: support per-distpatch_queue flush machinery This patch supports to run one single flush machinery for each blk-mq dispatch queue, so that: - current init_request and exit_request callbacks can cover flush request too, then the buggy copying way of initializing flush request's pdu can be fixed - flushing performance gets improved in case of multi hw-queue In fio sync write test over virtio-blk(4 hw queues, ioengine=sync, iodepth=64, numjobs=4, bs=4K), it is observed that througput gets increased a lot over my test environment: - throughput: +70% in case of virtio-blk over null_blk - throughput: +30% in case of virtio-blk over SSD image The multi virtqueue feature isn't merged to QEMU yet, and patches for the feature can be found in below tree: git://kernel.ubuntu.com/ming/qemu.git v2.1.0-mq.4 And simply passing 'num_queues=4 vectors=5' should be enough to enable multi queue(quad queue) feature for QEMU virtio-blk. Suggested-by: Christoph Hellwig Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- block/blk-flush.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) (limited to 'block/blk-flush.c') diff --git a/block/blk-flush.c b/block/blk-flush.c index 004d95e4098e..20badd7b9d1b 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -305,8 +305,15 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq) fq->flush_pending_idx ^= 1; blk_rq_init(q, flush_rq); - if (q->mq_ops) - blk_mq_clone_flush_request(flush_rq, first_rq); + + /* + * Borrow tag from the first request since they can't + * be in flight at the same time. + */ + if (q->mq_ops) { + flush_rq->mq_ctx = first_rq->mq_ctx; + flush_rq->tag = first_rq->tag; + } flush_rq->cmd_type = REQ_TYPE_FS; flush_rq->cmd_flags = WRITE_FLUSH | REQ_FLUSH_SEQ; @@ -480,22 +487,22 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, } EXPORT_SYMBOL(blkdev_issue_flush); -struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q) +struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q, + int node, int cmd_size) { struct blk_flush_queue *fq; int rq_sz = sizeof(struct request); - fq = kzalloc(sizeof(*fq), GFP_KERNEL); + fq = kzalloc_node(sizeof(*fq), GFP_KERNEL, node); if (!fq) goto fail; if (q->mq_ops) { spin_lock_init(&fq->mq_flush_lock); - rq_sz = round_up(rq_sz + q->tag_set->cmd_size, - cache_line_size()); + rq_sz = round_up(rq_sz + cmd_size, cache_line_size()); } - fq->flush_rq = kzalloc(rq_sz, GFP_KERNEL); + fq->flush_rq = kzalloc_node(rq_sz, GFP_KERNEL, node); if (!fq->flush_rq) goto fail_rq; -- cgit