From nobody Fri Dec 19 12:13:18 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2AB8C268C42; Fri, 10 Oct 2025 02:28:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760063322; cv=none; b=K0rvQchN8n9UDpP2da427Gg61aijrhzrQMKKNWO6A/NF0FzBopSjbVAe51z2tcVZ0KxrPFUWTnl2PsQmX+Tp4KJIiy48YjnYyYlGEIPZE1pAAxXbW0kNr1dt1umdQ0OFHGTl7PWBjLWDAhkcj+eAiqrf0bACoIsUgTqTc1JmDLc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760063322; c=relaxed/simple; bh=FK9xKviTcI/C/LX0yN/JGLOVejrI+c9f1E6gl9PnytQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=gtPum16gswonQPC3YSA3KWLoS4peJmd/EZZEJ5Tk0j64cvn+mQKTC01Sck4D3jLqJDVMEoyOlJzUQGSymYpTmxz32s1eQRYp8SarLpnsILKBUKwEkukiFyApQe4w3bWr0E7BAbUeBiRWBs3E1TJzmaGisLOV3z9BXRDkSWWzP2g= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Bndp/sPY; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Bndp/sPY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED887C4CEF7; Fri, 10 Oct 2025 02:28:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760063322; bh=FK9xKviTcI/C/LX0yN/JGLOVejrI+c9f1E6gl9PnytQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Bndp/sPYydcCNDbqrXtjVXk/W675XXogzGiv+wYQO7RUr4O7Qb323sK7694qpUdEB j5Wmyok32ASruvnzXq2Wju1+WutiK3Ql+cvY9VIgTVJ0fSOggPEiK2pOUL2LnZrGXP 7MV0NvitQ8m8fJYIVrQHQCcSbwmVP5PJqlMGkaWVb0ptGQRoafeCgF7qyLELfyXdD9 mGDKGey91KwMJTKM21onErVPUAVbS/Cke52c6KzTNY0IR6A74dHjFVE2Z6RxKzuR9R 1EmjpsdWk6l62UzbYDrcD7uHVguKiwM9BwNkgf9sSoM3Kxohizt46BF2+kVK5eyAy1 QeYbPuk8Cz35Q== From: Yu Kuai To: axboe@kernel.dk, bvanassche@acm.org, nilay@linux.ibm.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [PATCH v3 7/7] blk-mq: add documentation for new queue attribute async_dpeth Date: Fri, 10 Oct 2025 10:28:09 +0800 Message-ID: <20251010022812.2985286-8-yukuai@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251010022812.2985286-1-yukuai@kernel.org> References: <20251010022812.2985286-1-yukuai@kernel.org> 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 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 2.51.0