From nobody Tue Dec 2 01:51:04 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 42F092FA0F3; Fri, 21 Nov 2025 05:29:23 +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=1763702963; cv=none; b=MozQ2j7psZ4md3uUSfCNmJ5IB7vo0x6QDIxUMn2W4sJZdjqh39c11bNUlL/qO4yiwoAZDQUHzsZ8FFFf8ZPe8w3ez9wVoWqyNAClb2N4uolH05lDV29XtEStnjvtQP9T0tpM9L55PaD0cWfDiSu9h+NxxpP5dSTe3HQ8MHy5wM4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763702963; c=relaxed/simple; bh=P4zluyjrFatEHzqDCNyTnPlLpi7Qnyr/jRYxL32Ruhw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=giizA2tuVXflDhs8cVT1iuvgVoK/uueIlJ38tv0pCubkb05YFYqv5VUOQO1W0u3Pk3fosEkQ9d3ccJtBiGOwZ9VDPB8hmUXaRLElWzFp17IEfJ6VVlo9fgMwnNRy6DMSUpnmHPsEXYgjkFWNecUAbSMH7vWErcFuYu4LKzRVvCE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id D96A9C4AF0B; Fri, 21 Nov 2025 05:29:20 +0000 (UTC) From: Yu Kuai To: axboe@kernel.dk, nilay@linux.ibm.com, bvanassche@acm.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Cc: yukuai@fnnas.com Subject: [PATCH v6 8/8] blk-mq: add documentation for new queue attribute async_dpeth Date: Fri, 21 Nov 2025 13:28:55 +0800 Message-ID: <20251121052901.1341976-9-yukuai@fnnas.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251121052901.1341976-1-yukuai@fnnas.com> References: <20251121052901.1341976-1-yukuai@fnnas.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 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