From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0EC9C49ED6 for ; Wed, 11 Sep 2019 14:47:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD0DB2081B for ; Wed, 11 Sep 2019 14:47:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727581AbfIKOrr (ORCPT ); Wed, 11 Sep 2019 10:47:47 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:56894 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727020AbfIKOrr (ORCPT ); Wed, 11 Sep 2019 10:47:47 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id 467DE260785 From: =?UTF-8?q?Andr=C3=A9=20Almeida?= To: linux-block@vger.kernel.org, linux-doc@vger.kernel.org Cc: corbet@lwn.net, axboe@kernel.dk, m@bjorling.me, kernel@collabora.com, krisman@collabora.com, =?UTF-8?q?Andr=C3=A9=20Almeida?= Subject: [PATCH 1/3] docs: block: null_blk: enhance document style Date: Wed, 11 Sep 2019 11:46:34 -0300 Message-Id: <20190911144636.226945-1-andrealmeid@collabora.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Use proper ReST syntax for chapters. Add more information to enhance standardization in the file and to make the rendering more homogeneous. Add a SPDX identifier. Mark single-queue mode as deprecated. Signed-off-by: André Almeida --- I've asked the file creator (Matias Bjørling ), and he confirmed that I could use GPL-2.0 for this file. Documentation/block/null_blk.rst | 33 +++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-) diff --git a/Documentation/block/null_blk.rst b/Documentation/block/null_blk.rst index 31451d80783c..edbbab2f12f8 100644 --- a/Documentation/block/null_blk.rst +++ b/Documentation/block/null_blk.rst @@ -1,19 +1,16 @@ +.. SPDX-License-Identifier: GPL-2.0 + ======================== Null block device driver ======================== -1. Overview -=========== +Overview +======== -The null block device (/dev/nullb*) is used for benchmarking the various +The null block device (``/dev/nullb*``) is used for benchmarking the various block-layer implementations. It emulates a block device of X gigabytes in size. -The following instances are possible: - - Single-queue block-layer - - - Request-based. - - Single submission queue per device. - - Implements IO scheduling algorithms (CFQ, Deadline, noop). +It does not execute any read/write operation, just mark them as complete in +the request queue. The following instances are possible: Multi-queue block-layer @@ -27,15 +24,15 @@ The following instances are possible: All of them have a completion queue for each core in the system. -2. Module parameters applicable for all instances -================================================= +Module parameters +================= queue_mode=[0-2]: Default: 2-Multi-queue Selects which block-layer the module should instantiate with. = ============ 0 Bio-based - 1 Single-queue + 1 Single-queue (deprecated) 2 Multi-queue = ============ @@ -67,7 +64,7 @@ irqmode=[0-2]: Default: 1-Soft-irq completion_nsec=[ns]: Default: 10,000ns Combined with irqmode=2 (timer). The time each completion event must wait. -submit_queues=[1..nr_cpus]: +submit_queues=[1..nr_cpus]: Default: 1 The number of submission queues attached to the device driver. If unset, it defaults to 1. For multi-queue, it is ignored when use_per_node_hctx module parameter is 1. @@ -75,9 +72,11 @@ submit_queues=[1..nr_cpus]: hw_queue_depth=[0..qdepth]: Default: 64 The hardware queue depth of the device. -III: Multi-queue specific parameters +Multi-queue specific parameters +------------------------------- use_per_node_hctx=[0/1]: Default: 0 + Number of hardware context queues. = ===================================================================== 0 The number of submit queues are set to the value of the submit_queues @@ -87,6 +86,7 @@ use_per_node_hctx=[0/1]: Default: 0 = ===================================================================== no_sched=[0/1]: Default: 0 + Enable/disable the io scheduler. = ====================================== 0 nullb* use default blk-mq io scheduler @@ -94,6 +94,7 @@ no_sched=[0/1]: Default: 0 = ====================================== blocking=[0/1]: Default: 0 + Blocking behavior of the request queue. = =============================================================== 0 Register as a non-blocking blk-mq driver device. @@ -103,6 +104,7 @@ blocking=[0/1]: Default: 0 = =============================================================== shared_tags=[0/1]: Default: 0 + Sharing tags between devices. = ================================================================ 0 Tag set is not shared. @@ -111,6 +113,7 @@ shared_tags=[0/1]: Default: 0 = ================================================================ zoned=[0/1]: Default: 0 + Device is a random-access or a zoned block device. = ====================================================================== 0 Block device is exposed as a random-access block device. -- 2.23.0