From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 482793B9601 for ; Thu, 30 Jul 2026 08:30:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785400204; cv=none; b=l6P3Mml+0WhtozOv0jNKVXwJNg1OBg/hPEWFNSjMw+4M4WncB4BMPSOyEF6MxMBdUzWc1/1j69VXSF19zZo9bTGN++pYrmy12aMLb5AbnPYbWIPkERrXcUXoNur+YlXUZgJhZ0dilDTbg0FGRRZpcNNyjwY2h10vlsVtTyYrfA4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785400204; c=relaxed/simple; bh=WjJD/8PjLMwS5siUDguvYZnvopvVVZ9H0vkzAKHd7/Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c7Cz9DHyhT0u704dFyN/99KCJWKE7FTaaDsnVt9VcLBFkppxqveAAIB8AaDYH5qItXHmzBu7ok4V0dF+t30PyUXF/qvFzcyRqPrKVESnazTNm+avm2q89ViUBrfXPoUVpIA4WkRv4vNKTU3mL6jH/nR/Rc44BksmkFJz6KP69As= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=huawei.com; spf=none smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.198]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4h9j624t1nzKHMPf for ; Thu, 30 Jul 2026 16:28:58 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id 1A91D40EDD for ; Thu, 30 Jul 2026 16:29:55 +0800 (CST) Received: from huaweicloud.com (unknown [10.50.85.155]) by APP3 (Coremail) with UTF8SMTPSA id _Ch0CgCnlkV9C2tqwObjAQ--.20420S12; Thu, 30 Jul 2026 16:29:54 +0800 (CST) From: Yang Erkun To: josef@toxicpanda.com, axboe@kernel.dk, hch@lst.de, yukuai@kernel.org Cc: yi.zhang@huawei.com, chengzhihao1@huawei.com, echo.chenlin@huawei.com, leo.lilong@huaweicloud.com, wangkefeng.wang@huawei.com, huawei.libin@huawei.com, leijitang@huawei.com, linux-block@vger.kernel.org, nbd@other.debian.org Subject: [PATCH v5 8/8] nbd: add nr_hw_queues module parameter for pre-created devices Date: Thu, 30 Jul 2026 16:20:46 +0800 Message-ID: <20260730082046.3459239-9-yangerkun@huawei.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260730082046.3459239-1-yangerkun@huawei.com> References: <20260730082046.3459239-1-yangerkun@huawei.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_Ch0CgCnlkV9C2tqwObjAQ--.20420S12 X-Coremail-Antispam: 1UD129KBjvJXoW7Zw4rXrW5WryUtF1DAFyDAwb_yoW8tr4DpF W5JFZrKFWxKr43ZaykXws7WF1UJa4UCa4xWF1xt3y8ur1rZ3ZavF97tFW5X3yUtF9xAa1Y y3Z8AFs7Cr1UArJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUQjb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIEc7Cj xVAFwI0_GcCE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrV C2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE 7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262 kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCF04k20xvEw4C26cxK6c8Ij28IcwCFx2Iq xVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r 106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AK xVWUCVW8JwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20x vaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8 Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x07UZyCLUUUUU= Sender: yangerkun@huaweicloud.com X-CM-SenderInfo: 51dqwvhunx0q5kxd4v5lfo033gof0z/ The function blk_mq_update_nr_hw_queues in nbd_start_device may causes a queue freeze. The previous commit addressed this issue for newly created nbd device via setting the expected nr_hw_queues in nbd_dev_add. However, when reusing an old inactive nbd device, the queue freeze can still occur when old nbd->tag_set->nr_hw_queues not match the new socket connection count. Inactive nbd devices can originate from two sources: loading the nbd module with nbds_max, which sets the default nr_hw_queues to 1, and the netlink method, which sets nr_hw_queues according to the expected number of socket connections. For the first case, we can add a module parameter to allow changing the default nr_hw_queues. This way, users who know their expected number of connections can prevent queue freezes on pre-created devices via nbds_max. Before this patchset: real 0m2.195s user 0m0.005s sys 0m0.022s After this patchset: real 0m0.090s user 0m0.004s sys 0m0.018s Signed-off-by: Yang Erkun --- drivers/block/nbd.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 6369a409e10c..2194c7d7b2ea 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -166,6 +166,7 @@ static struct dentry *nbd_dbg_dir; static unsigned int nbds_max = 16; static int max_part = 16; +static int nr_hw_queues = 1; static int part_shift; static int nbd_dev_dbg_init(struct nbd_device *nbd); @@ -2740,8 +2741,10 @@ static int __init nbd_init(void) } nbd_dbg_init(); + if (nr_hw_queues < 1) + nr_hw_queues = 1; for (i = 0; i < nbds_max; i++) - nbd_dev_add(i, 1, 1); + nbd_dev_add(i, 1, nr_hw_queues); return 0; } @@ -2802,3 +2805,6 @@ module_param(nbds_max, int, 0444); MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)"); module_param(max_part, int, 0444); MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)"); +module_param(nr_hw_queues, int, 0444); +MODULE_PARM_DESC(nr_hw_queues, +"number of hardware queues for devices pre-created at module load (default: 1). "); -- 2.52.0