From b34ea3c91eacdc50c761506cab35b14f67216f76 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 6 Oct 2021 12:01:07 -0600 Subject: [PATCH] block: bump max plugged deferred size from 16 to 32 [ Upstream commit ba0ffdd8ce48ad7f7e85191cd29f9674caca3745 ] Particularly for NVMe with efficient deferred submission for many requests, there are nice benefits to be seen by bumping the default max plug count from 16 to 32. This is especially true for virtualized setups, where the submit part is more expensive. But can be noticed even on native hardware. Reduce the multiple queue factor from 4 to 2, since we're changing the default size. While changing it, move the defines into the block layer private header. These aren't values that anyone outside of the block layer uses, or should use. Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-mq.c | 4 ++-- block/blk.h | 6 ++++++ include/linux/blkdev.h | 2 -- 3 files changed, 8 insertions(+), 4 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 69cc552c3dfc..e4422a09b126 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2116,14 +2116,14 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq) } /* - * Allow 4x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple + * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple * queues. This is important for md arrays to benefit from merging * requests. */ static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug) { if (plug->multiple_queues) - return BLK_MAX_REQUEST_COUNT * 4; + return BLK_MAX_REQUEST_COUNT * 2; return BLK_MAX_REQUEST_COUNT; } diff --git a/block/blk.h b/block/blk.h index f84c83300f6f..997941cd999f 100644 --- a/block/blk.h +++ b/block/blk.h @@ -188,6 +188,12 @@ bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, void blk_account_io_start(struct request *req); void blk_account_io_done(struct request *req, u64 now); +/* + * Plug flush limits + */ +#define BLK_MAX_REQUEST_COUNT 32 +#define BLK_PLUG_FLUSH_SIZE (128 * 1024) + /* * Internal elevator interface */ diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 8aae375864b6..4ba17736b614 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1248,8 +1248,6 @@ struct blk_plug { bool multiple_queues; bool nowait; }; -#define BLK_MAX_REQUEST_COUNT 16 -#define BLK_PLUG_FLUSH_SIZE (128 * 1024) struct blk_plug_cb; typedef void (*blk_plug_cb_fn)(struct blk_plug_cb *, bool);