Commit 9d3d21ae authored May 10, 2014 by Ming Lei Committed by Jens Axboe May 10, 2014

blk-mq: bitmap tag: select random tag betweet 0 and (depth - 1)



The selected tag should be selected at random between 0 and
(depth - 1) with probability 1/depth, instead between 0 and
(depth - 2) with probability 1/(depth - 1).

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 60f2df8a

block/blk-mq-tag.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -449,10 +449,7 @@ void blk_mq_tag_init_last_tag(struct blk_mq_tags tags, unsigned int tag)
		{
		unsigned int depth = tags->nr_tags - tags->nr_reserved_tags;

		if (depth > 1)
		*tag = prandom_u32() % (depth - 1);
		else
		*tag = 0;
		*tag = prandom_u32() % depth;
		}

		ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags tags, char page)