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-rw-r--r--block/blk-mq.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 65d3a63aecc6..108a352051be 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2135,6 +2135,18 @@ 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
+ * 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;
+}
+
/**
* blk_mq_submit_bio - Create and send a request to block device.
* @bio: Bio pointer.
@@ -2231,7 +2243,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio)
else
last = list_entry_rq(plug->mq_list.prev);
- if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
+ if (request_count >= blk_plug_max_rq_count(plug) || (last &&
blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
blk_flush_plug_list(plug, false);
trace_block_plug(q);