From patchwork Fri Oct 2 14:43:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 11813723 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 444246CB for ; Fri, 2 Oct 2020 14:45:08 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EA20F206FA for ; Fri, 2 Oct 2020 14:45:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CMdrrBc2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EA20F206FA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:58138 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kOMJ1-0003M8-2w for patchwork-qemu-devel@patchwork.kernel.org; Fri, 02 Oct 2020 10:45:07 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34274) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kOMHz-00016w-23 for qemu-devel@nongnu.org; Fri, 02 Oct 2020 10:44:03 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:39245) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kOMHw-0004Ux-De for qemu-devel@nongnu.org; Fri, 02 Oct 2020 10:44:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601649839; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L//1CGUj0rBYcxSReEPLJ4l43MPjZ/l65bBuwUSb4fk=; b=CMdrrBc25O8hYlQNCqGP4J3QtMJoFOl7NGzj1GfzYtLZfGy1jZy8FHrX/pboFh2yktLVgR 6RzmJ4dubEaK65jjmerP8+ZK9Xi67xGutZ5hBz/V2CH08fcDBLpZsw7LivoUypR0kz0bJZ vce9tWYdIJMxjy3cd2t06+vIWL7mbrU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-514-uqOErNMsPFWiFrOwDtC0fw-1; Fri, 02 Oct 2020 10:43:56 -0400 X-MC-Unique: uqOErNMsPFWiFrOwDtC0fw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F07FC1084C93; Fri, 2 Oct 2020 14:43:54 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-112-139.ams2.redhat.com [10.36.112.139]) by smtp.corp.redhat.com (Postfix) with ESMTP id 06F445D9D5; Fri, 2 Oct 2020 14:43:53 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PULL 03/37] docs: Document the throttle block filter Date: Fri, 2 Oct 2020 16:43:11 +0200 Message-Id: <20201002144345.253865-4-kwolf@redhat.com> In-Reply-To: <20201002144345.253865-1-kwolf@redhat.com> References: <20201002144345.253865-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/01 23:37:29 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Alberto Garcia This filter was added back in 2017 for QEMU 2.11 but it was never properly documented, so let's explain how it works and add a couple of examples. Signed-off-by: Alberto Garcia Message-Id: <20200921173016.27935-1-berto@igalia.com> Signed-off-by: Kevin Wolf --- docs/throttle.txt | 108 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 107 insertions(+), 1 deletion(-) diff --git a/docs/throttle.txt b/docs/throttle.txt index cd4e109d39..b5b78b7326 100644 --- a/docs/throttle.txt +++ b/docs/throttle.txt @@ -1,6 +1,6 @@ The QEMU throttling infrastructure ================================== -Copyright (C) 2016 Igalia, S.L. +Copyright (C) 2016,2020 Igalia, S.L. Author: Alberto Garcia This work is licensed under the terms of the GNU GPL, version 2 or @@ -253,3 +253,109 @@ up. After those 60 seconds the bucket will have leaked 60 x 100 = Also, due to the way the algorithm works, longer burst can be done at a lower I/O rate, e.g. 1000 IOPS during 120 seconds. + + +The 'throttle' block filter +--------------------------- +Since QEMU 2.11 it is possible to configure the I/O limits using a +'throttle' block filter. This filter uses the exact same throttling +infrastructure described above but can be used anywhere in the node +graph, allowing for more flexibility. + +The user can create an arbitrary number of filters and each one of +them must be assigned to a group that contains the actual I/O limits. +Different filters can use the same group so the limits are shared as +described earlier in "Applying I/O limits to groups of disks". + +A group can be created using the object-add QMP function: + + { "execute": "object-add", + "arguments": { + "qom-type": "throttle-group", + "id": "group0", + "props": { + "limits" : { + "iops-total": 1000 + "bps-write": 2097152 + } + } + } + } + +throttle-group has a 'limits' property (of type ThrottleLimits as +defined in qapi/block-core.json) which can be set on creation or later +with 'qom-set'. + +A throttle-group can also be created with the -object command line +option but at the moment there is no way to pass a 'limits' parameter +that contains a ThrottleLimits structure. The solution is to set the +individual values directly, like in this example: + + -object throttle-group,id=group0,x-iops-total=1000,x-bps-write=2097152 + +Note however that this is not a stable API (hence the 'x-' prefixes) and +will disappear when -object gains support for structured options and +enables use of 'limits'. + +Once we have a throttle-group we can use the throttle block filter, +where the 'file' property must be set to the block device that we want +to filter: + + { "execute": "blockdev-add", + "arguments": { + "options": { + "driver": "qcow2", + "node-name": "disk0", + "file": { + "driver": "file", + "filename": "/path/to/disk.qcow2" + } + } + } + } + + { "execute": "blockdev-add", + "arguments": { + "driver": "throttle", + "node-name": "throttle0", + "throttle-group": "group0", + "file": "disk0" + } + } + +A similar setup can also be done with the command line, for example: + + -drive driver=throttle,throttle-group=group0, + file.driver=qcow2,file.file.filename=/path/to/disk.qcow2 + +The scenario described so far is very simple but the throttle block +filter allows for more complex configurations. For example, let's say +that we have three different drives and we want to set I/O limits for +each one of them and an additional set of limits for the combined I/O +of all three drives. + +First we would define all throttle groups, one for each one of the +drives and one that would apply to all of them: + + -object throttle-group,id=limits0,x-iops-total=2000 + -object throttle-group,id=limits1,x-iops-total=2500 + -object throttle-group,id=limits2,x-iops-total=3000 + -object throttle-group,id=limits012,x-iops-total=4000 + +Now we can define the drives, and for each one of them we use two +chained throttle filters: the drive's own filter and the combined +filter. + + -drive driver=throttle,throttle-group=limits012, + file.driver=throttle,file.throttle-group=limits0 + file.file.driver=qcow2,file.file.file.filename=/path/to/disk0.qcow2 + -drive driver=throttle,throttle-group=limits012, + file.driver=throttle,file.throttle-group=limits1 + file.file.driver=qcow2,file.file.file.filename=/path/to/disk1.qcow2 + -drive driver=throttle,throttle-group=limits012, + file.driver=throttle,file.throttle-group=limits2 + file.file.driver=qcow2,file.file.file.filename=/path/to/disk2.qcow2 + +In this example the individual drives have IOPS limits of 2000, 2500 +and 3000 respectively but the total combined I/O can never exceed 4000 +IOPS.