From nobody Fri Dec 19 10:42:40 2025 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 9ADC12D46DD; Thu, 9 Oct 2025 07:53:21 +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=1759996403; cv=none; b=n7gAgcQiB+0bbxIGyiBI/DLxcdjLcaQg7N+KeNwJeMDi4gQ/GsphGquSp8IkjnK8D33aU0fcZZOzZF0RYx6c6mt7YYQLyhfhqBXL89IFPgVgvKuXKftykKe99uEdMQyojKoC3cQEf8DT4gQXLlTm/ZaHWEtlxd6FGBTfkjqdL/c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759996403; c=relaxed/simple; bh=DWJV6xc4X74tdFQ7VC3xAlPi68hmaXItok1qFJhL6Ec=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=fAHoS50VZxnnNbZHcaFFwf1o735Yv8y8bwep/m30sCzTe52kZqDGLw2E1IKhAeXwq3rhHOREwPYoc3iKeEW0rgK6Yi3qYcHSSUTbBcPeiB7OtKbQn9Wf4JHh4VpKkdUqoSv/mUpLSHJzowvnzS5JCEURcn0yAo4V7OiHonTEFsE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=none smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4cj2Cz61m2zKHMh1; Thu, 9 Oct 2025 15:52:47 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 61CBE1A15C8; Thu, 9 Oct 2025 15:53:16 +0800 (CST) Received: from huaweicloud.com (unknown [10.50.159.234]) by APP4 (Coremail) with SMTP id gCh0CgA3+mHqaedo7Fo7CQ--.38248S11; Thu, 09 Oct 2025 15:53:16 +0800 (CST) From: Yu Kuai To: axboe@kernel.dk, bvanassche@acm.org, ming.lei@redhat.com, nilay@linux.ibm.com, jmoyer@redhat.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [patch v2 7/7] blk-mq: add documentation for new queue attribute async_dpeth Date: Thu, 9 Oct 2025 15:46:34 +0800 Message-Id: <20251009074634.527661-8-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20251009074634.527661-1-yukuai1@huaweicloud.com> References: <20251009074634.527661-1-yukuai1@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: gCh0CgA3+mHqaedo7Fo7CQ--.38248S11 X-Coremail-Antispam: 1UD129KBjvJXoW7uFW7Xr4rAF1kJw4kXF1DZFb_yoW8ur1Up3 yrtr47Ka4rXF17uryfAr1S9r4ft395Xr17Grsxt3WUXr98uwnrGFZaqr45XFn7ZryfJw4j 9rWDuF98Ga42yw7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUma14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkE bVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67 AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUCVW8JwCI 42IY6xIIjxv20xvEc7CjxVAFwI0_Cr0_Gr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCw CI42IY6I8E87Iv67AKxVW8JVWxJwCI42IY6I8E87Iv6xkF7I0E14v26r4UJVWxJrUvcSsG vfC2KfnxnUUI43ZEXa7VUbPC7UUUUUU== X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ From: Yu Kuai Explain the attribute and the default value in different case. Signed-off-by: Yu Kuai Reviewed-by: Nilay Shroff --- Documentation/ABI/stable/sysfs-block | 34 ++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stabl= e/sysfs-block index 0ed10aeff86b..aa1e94169666 100644 --- a/Documentation/ABI/stable/sysfs-block +++ b/Documentation/ABI/stable/sysfs-block @@ -609,6 +609,40 @@ Description: enabled, and whether tags are shared. =20 =20 +What: /sys/block//queue/async_depth +Date: August 2025 +Contact: linux-block@vger.kernel.org +Description: + [RW] Controls how many asynchronous requests may be allocated in the + block layer. The value is always capped at nr_requests. + + When no elevator is active (none): + - async_depth is always equal to nr_requests. + + For bfq scheduler: + - By default, async_depth is set to 75% of nr_requests. + Internal limits are then derived from this value: + * Sync writes: limited to async_depth (=E2=89=8875% of nr_requests). + * Async I/O: limited to ~2/3 of async_depth (=E2=89=8850% of nr_reques= ts). + + If a bfq_queue is weight-raised: + * Sync writes: limited to ~1/2 of async_depth (=E2=89=8837% of nr_requ= ests). + * Async I/O: limited to ~1/4 of async_depth (=E2=89=8818% of nr_reques= ts). + + - If the user writes a custom value to async_depth, BFQ will recompute + these limits proportionally based on the new value. + + For Kyber: + - By default async_depth is set to 75% of nr_requests. + - If the user writes a custom value to async_depth, then it override the + default and directly control the limit for writes and async I/O. + + For mq-deadline: + - By default async_depth is set to nr_requests. + - If the user writes a custom value to async_depth, then it override the + default and directly control the limit for writes and async I/O. + + What: /sys/block//queue/nr_zones Date: November 2018 Contact: Damien Le Moal --=20 2.39.2