From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757345AbaEJRCb (ORCPT ); Sat, 10 May 2014 13:02:31 -0400 Received: from mail-pd0-f172.google.com ([209.85.192.172]:60115 "EHLO mail-pd0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757055AbaEJRC3 (ORCPT ); Sat, 10 May 2014 13:02:29 -0400 From: Ming Lei To: Jens Axboe , linux-kernel@vger.kernel.org Cc: Ming Lei 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 Message-Id: <1399741312-10453-4-git-send-email-tom.leiming@gmail.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1399741312-10453-1-git-send-email-tom.leiming@gmail.com> References: <1399741312-10453-1-git-send-email-tom.leiming@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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