[PATCH 4/4] blk-mq: mark ctx as pending at batch in flush plug path

From: Ming Lei
Date: Tue Oct 13 2015 - 23:31:19 EST


Most of times, flush plug should be the hottest I/O path,
so mark ctx as pending after all requests in the list are
inserted.

Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
---
block/blk-mq.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index deb5f4c..1c943b9 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -993,18 +993,25 @@ void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
}
EXPORT_SYMBOL(blk_mq_delay_queue);

-static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
- struct request *rq, bool at_head)
+static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
+ struct blk_mq_ctx *ctx,
+ struct request *rq,
+ bool at_head)
{
- struct blk_mq_ctx *ctx = rq->mq_ctx;
-
trace_block_rq_insert(hctx->queue, rq);

if (at_head)
list_add(&rq->queuelist, &ctx->rq_list);
else
list_add_tail(&rq->queuelist, &ctx->rq_list);
+}
+
+static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
+ struct request *rq, bool at_head)
+{
+ struct blk_mq_ctx *ctx = rq->mq_ctx;

+ __blk_mq_insert_req_list(hctx, ctx, rq, at_head);
blk_mq_hctx_mark_pending(hctx, ctx);
}

@@ -1060,8 +1067,9 @@ static void blk_mq_insert_requests(struct request_queue *q,
rq = list_first_entry(list, struct request, queuelist);
list_del_init(&rq->queuelist);
rq->mq_ctx = ctx;
- __blk_mq_insert_request(hctx, rq, false);
+ __blk_mq_insert_req_list(hctx, ctx, rq, false);
}
+ blk_mq_hctx_mark_pending(hctx, ctx);
spin_unlock(&ctx->lock);

blk_mq_run_hw_queue(hctx, from_schedule);
--
1.9.1

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