From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 C6A8A41E6A8 for ; Tue, 4 Aug 2026 08:48:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785833340; cv=none; b=uUnODJxenrR6XJz78TnVwyTF4Nu4ZrLftKx8ZU2VKRvgszHhjnXRlmmJoXCd1a+MvBXIsytEpkPRlxDW9zZ/Nhkxhp+Va53T/hQPlnqnJxUu9ESJqVBh0ts5gcn+nVIzOQL3g0zmSXdykFSd3MPUZpUOvIho/zNIKFWgX/brwnA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785833340; c=relaxed/simple; bh=AD5qyR3wOXQhlR+fKMAnX6/bgFIXObOVwWP7vpAwenc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=S7Hkll6OyNT+W1dl9gJSpiH9eNDpcTBAEO8AXgbHqV0zu7K3UofxZwB03nSbUBtomxcGvVPUcrlsSAE/oCYFWAemyESa/M+4u1fA66gFb55drmQ2nUU/Jb0odufdKGRxizd4cHUySqtCgiXL823RzJ3rE+ehAWw2/hPMwijVA/w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.198]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4hDnHc5113zYQv3d for ; Tue, 4 Aug 2026 16:47:56 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id BCD2340A87 for ; Tue, 4 Aug 2026 16:48:47 +0800 (CST) Received: from huaweicloud.com (unknown [10.50.85.155]) by APP3 (Coremail) with UTF8SMTPSA id _Ch0CgD35kVrp3Fq71VIBA--.52677S4; Tue, 04 Aug 2026 16:48:47 +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 v6 0/8] nbd: eliminate queue freeze/unfreeze overhead in connection setup Date: Tue, 4 Aug 2026 16:39:14 +0800 Message-ID: <20260804083922.1927105-1-yangerkun@huawei.com> X-Mailer: git-send-email 2.52.0 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:_Ch0CgD35kVrp3Fq71VIBA--.52677S4 X-Coremail-Antispam: 1UD129KBjvJXoW7WFyxArWkJrWDXw48Gr4xCrg_yoW8Cw15pF WfKFy3Kr40qF43XrsxZw18W3WYqw4kCr9xGF17J340kF1Yka4vqFWIv34Fyay7Ar9a9w12 va1YqrZ7Cayj9FJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9qb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVWxJr0_GcWl84ACjcxK6I8E87Iv6xkF7I 0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40E x7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x 0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxVAa w2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l42xK82IY64kExVAvwVAq07x20xyl4I8I3I 0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWU GVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI 0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0 rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r 4UJbIYCTnIWIevJa73UjIFyTuYvjxUF0PfDUUUU Sender: yangerkun@huaweicloud.com X-CM-SenderInfo: 51dqwvhunx0q5kxd4v5lfo033gof0z/ This series eliminates the blk_mq_freeze_queue()/unfreeze_queue() overhead that currently occurs during nbd connection setup(nbd provide ondemand and was using in AI sandbox e2b[1] to mount and attach rootfs). Each freeze cycle will introduce a RCU grace which was significant with multi-core system. time nbd-client --name myexport --connections 96 127.0.0.1 1234 After this patchset: real 0m0.090s user 0m0.004s sys 0m0.018s Without this patchset: real 0m2.195s user 0m0.005s sys 0m0.022s v5->v6: 1. patch 3, reset stale FEAT*, not only write cache 2. patch 5, using the way Kuai advise to skip freeze 3. patch 6, adopt kuai's suggestion 4. patch 8, rename nr_hw_queues and add some comments v4->v5: 1. add patch 3 to reset write cache on disconnect 2. fix ("nbd: factor out a nbd_genl_foreach_sock") v3->v4: 1. factor out nbd_genl_foreach_sock to cleanup duplicated code 2. rewrite some commit message to make what's going more clearly v2->v3: 1. Stop using xarray, and protect it by rejecting late NBD_SET_SOCKS 2. Eliminate freeze in nbd_set_size when device setup 3. Add module parameter to eliminate freeze for pre-created device v1->v2: 1. Rewrite cover letter 2. Eliminate freeze call from blk_mq_update_nr_hw_queues in nbd_start_device for netlink path Long Li (1): nbd: simplify find_fallback() by removing redundant logic Yang Erkun (7): nbd: disallow NBD_SET_SOCK on an active device nbd: clear queue limits on disconnect nbd: remove queue freeze in nbd_add_socket nbd: skip queue freeze when setting size at device startup nbd: factor out a nbd_genl_foreach_sock nbd: remove queue freeze for newly created nbd from netlink path nbd: add pre_defined_connections module parameter for pre-created devices drivers/block/nbd.c | 255 +++++++++++++++++++++++--------------------- 1 file changed, 136 insertions(+), 119 deletions(-) -- 2.52.0