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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 D10EDC433F5 for ; Wed, 22 Sep 2021 12:49:15 +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 6A26D610A0 for ; Wed, 22 Sep 2021 12:49:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 6A26D610A0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:49246 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mT1gY-00074R-AU for qemu-devel@archiver.kernel.org; Wed, 22 Sep 2021 08:49:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44002) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mT1dD-0004Ka-CN for qemu-devel@nongnu.org; Wed, 22 Sep 2021 08:45:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:22404) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mT1d8-0002E4-IU for qemu-devel@nongnu.org; Wed, 22 Sep 2021 08:45:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632314740; 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=5Hr12uIVIGuRGIipdmTDfM4S/Wjxx3R2l7hlwcsNYQA=; b=Bmiobx1HarxxDacqqmIJYjdFORX8Sbdbrm/u4MrRtJKxb2bpwdt7DFWoIBkP1RlEO6OLV/ +c9mCItp9dLx1Axk6eqHptZfDzwVNDLu9ZyQS7AiPVJgYTrQx3ADV4M0jk1/v29ftCrcgc vJYzWPVhEPL1b3hGwp1i/V5l0kPDTQk= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-426-2NUl-Am8O360Sn9g5ug00g-1; Wed, 22 Sep 2021 08:45:39 -0400 X-MC-Unique: 2NUl-Am8O360Sn9g5ug00g-1 Received: by mail-wr1-f72.google.com with SMTP id e1-20020adfa741000000b0015e424fdd01so2044603wrd.11 for ; Wed, 22 Sep 2021 05:45:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:from:to:cc:references:organization :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=5Hr12uIVIGuRGIipdmTDfM4S/Wjxx3R2l7hlwcsNYQA=; b=eUB4pEM11gS2Dii6L9hCxTC+rH4ojrQtaujDFt3liuuX1eYnPSuUTTE9XkguOIOEg3 cDK5/eF/U26ej73sVaeG3lklGQbliVEAgfxnV9Y5IidZMwgOnPTwyKLsWzw8MDYzTKhF vEwFk9X5dPRn8FA3Z/XJ/wyGm7CiwrBVCkk0ap7fS2/d8X5/njbgKc10oqTG6bTpd2Iw fUYBJX75FMJ5TQ51kCfUHUHRiTQsSMBGbv1nu51a1zV/SLx6flfqkiA6vCtE+2fNoEDx upkcJArIpMnmXR0Th8VfwjlEZB31NsRwJW8XR9MxCqRxAb7bZx6B5460sgOT+9NhHjkP AQWg== X-Gm-Message-State: AOAM532JMxXhs5FWPvAqWFyqya32YPgAqAxXMMWUE4kKEk7O2GnwxzzX J9nv2ETgnmYSohuRD5oTLxBWfjJp5UIcv4BQO6a/Uo2loRuh/1Nw0sO1kR3BPxLsosS9w+iS++F PzVo2qnEnUImBahI= X-Received: by 2002:adf:8b19:: with SMTP id n25mr44464195wra.216.1632314738288; Wed, 22 Sep 2021 05:45:38 -0700 (PDT) X-Google-Smtp-Source: ABdhPJw1UgqVKqqv+OwmlG9EsBmZZaBnsdYjUqeDqD6xwYrLDUaZEwEzLX6h98DnqtS4Lkbyb2pcPQ== X-Received: by 2002:adf:8b19:: with SMTP id n25mr44464170wra.216.1632314738050; Wed, 22 Sep 2021 05:45:38 -0700 (PDT) Received: from [192.168.3.132] (p5b0c64dd.dip0.t-ipconnect.de. [91.12.100.221]) by smtp.gmail.com with ESMTPSA id s15sm2169384wrb.22.2021.09.22.05.45.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 Sep 2021 05:45:37 -0700 (PDT) Subject: Re: [PATCH v1] monitor: Consider "id" when rate-limiting MEMORY_DEVICE_SIZE_CHANGE qapi events From: David Hildenbrand To: Markus Armbruster References: <20210921102434.24273-1-david@redhat.com> <878rzolsim.fsf@dusky.pond.sub.org> <3f70fe6d-d7b3-5a51-df5f-b4cd3efa7a36@redhat.com> Organization: Red Hat Message-ID: <13509a92-7be0-ae59-fa0e-1d45ca4fc0ff@redhat.com> Date: Wed, 22 Sep 2021 14:45:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <3f70fe6d-d7b3-5a51-df5f-b4cd3efa7a36@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.472, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-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: "Michael S . Tsirkin" , Michal Privoznik , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , Igor Mammedov , Eric Blake Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 22.09.21 14:20, David Hildenbrand wrote: > On 22.09.21 14:11, Markus Armbruster wrote: >> David Hildenbrand writes: >> >>> We have to consider the device id, otherwise we'll lose some events for >>> unrelated devices. If the device does not have a device id (very unlikely), >>> the target of the notifications has to update the size of all devices >>> manually either way. >>> >>> This was noticed by starting a VM with two virtio-mem devices that each >>> have a requested size > 0. The Linux guest will initialize both devices >>> in parallel, resulting in losing MEMORY_DEVICE_SIZE_CHANGE events for >>> one of the devices. >> >> Fascinating. >> >> Event rate limiting works as follows. >> >> An event is rate-limited when monitor_qapi_event_conf[event].rate != 0. >> >> When such an event arrives, it is held in a bucket until a timer >> associated with the bucket expires. Putting an event in an empty bucket >> starts its timer. Putting an event in a non-empty bucket replaces its >> old contents. >> >> The bucket to use for an event depends on its event type, and for some >> events also on certain event arguments. >> >> This patch solves the "MEMORY_DEVICE_SIZE_CHANGE events from different >> devices eat each other" by splitting the event's bucket. > > Right, that's how it's getting used in libvirt where we noticed it. > >> >> The split is imperfect: each device with a qdev ID gets its own bucket, >> all devices without ID have to share a bucket. > > Yes, it's far from perfect. Fortunately upper layers (libvirt) barely do > that. > >> >> This is actually a flaw in the event's design: you can't distinguish >> events from different devices without IDs. >> >> To fix that flaw, add the QOM path to the event. > > So the idea would be to extend the event by an optional QOM path > (because it's an existing event), but always setting it internally? > Thinking about it, not optional, because we always have a QOM path and extending an event with something not optional should just work AFAIKT. Just implemented it, seems to work just fine. Will send a v2 -- thanks! -- Thanks, David / dhildenb