From: Ming Lei <tom.leiming@gmail.com>
To: Jens Axboe <axboe@kernel.dk>, linux-kernel@vger.kernel.org
Cc: Ming Lei <tom.leiming@gmail.com>
Subject: [PATCH 3/5] blk-mq: bitmap tag: select random tag betweet 0 and (depth - 1)
Date: Sun, 11 May 2014 01:01:50 +0800 [thread overview]
Message-ID: <1399741312-10453-4-git-send-email-tom.leiming@gmail.com> (raw)
In-Reply-To: <1399741312-10453-1-git-send-email-tom.leiming@gmail.com>
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>
---
block/blk-mq-tag.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 777aad7..77d2b18 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -427,7 +427,7 @@ 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;
- *tag = prandom_u32() % (depth - 1);
+ *tag = prandom_u32() % depth;
}
ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page)
--
1.7.9.5
next prev parent reply other threads:[~2014-05-10 17:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-10 17:01 [PATCH 0/5] blk-mq: bitmap tag: fix and cleanup Ming Lei
2014-05-10 17:01 ` [PATCH 1/5] blk-mq: bitmap tag: use clear_bit_unlock in bt_clear_tag() Ming Lei
2014-05-10 17:01 ` [PATCH 2/5] blk-mq: bitmap tag: remove barrier " Ming Lei
2014-05-10 17:01 ` Ming Lei [this message]
2014-05-10 17:01 ` [PATCH 4/5] blk-mq: bitmap tag: cleanup blk_mq_init_tags Ming Lei
2014-05-10 17:01 ` [PATCH 5/5] blk-mq: bitmap tag: fix wait batch for allocation Ming Lei
2014-05-10 19:39 ` [PATCH 0/5] blk-mq: bitmap tag: fix and cleanup Jens Axboe
2014-05-11 1:13 ` Ming Lei
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