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=-7.0 required=3.0 tests=BAYES_00, 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 B17D9C433E1 for ; Thu, 27 Aug 2020 12:56:54 +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 86E932177B for ; Thu, 27 Aug 2020 12:56:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 86E932177B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:44482 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kBHSX-0001Wn-O4 for qemu-devel@archiver.kernel.org; Thu, 27 Aug 2020 08:56:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36444) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kBHRx-0000oz-CE for qemu-devel@nongnu.org; Thu, 27 Aug 2020 08:56:17 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:45346 helo=huawei.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kBHRu-0000Rn-2L for qemu-devel@nongnu.org; Thu, 27 Aug 2020 08:56:16 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id DC09838025CDDBCA56DD; Thu, 27 Aug 2020 20:55:58 +0800 (CST) Received: from [127.0.0.1] (10.174.186.4) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.487.0; Thu, 27 Aug 2020 20:55:52 +0800 Subject: Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function To: David Edmondson , , , , References: <1598260480-64862-1-git-send-email-zhengchuan@huawei.com> <1598260480-64862-12-git-send-email-zhengchuan@huawei.com> <1a23d60c-186b-d5b5-c43a-a8512826409b@huawei.com> From: Zheng Chuan Message-ID: Date: Thu, 27 Aug 2020 20:55:51 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.186.4] X-CFilter-Loop: Reflected Received-SPF: pass client-ip=45.249.212.32; envelope-from=zhengchuan@huawei.com; helo=huawei.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/27 08:55:59 X-ACL-Warn: Detected OS = Linux 3.11 and newer [fuzzy] X-Spam_score_int: -59 X-Spam_score: -6.0 X-Spam_bar: ------ X-Spam_report: (-6.0 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-1.782, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-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: zhang.zhanghailiang@huawei.com, qemu-devel@nongnu.org, xiexiangyou@huawei.com, alex.chen@huawei.com, ann.zhuangyanying@huawei.com, fangying1@huawei.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2020/8/27 19:58, David Edmondson wrote: > On Thursday, 2020-08-27 at 17:34:13 +08, Zheng Chuan wrote: > >>>> + /* >>>> + * Only support query once for each calculation, >>>> + * reset as DIRTY_RATE_STATUS_UNSTARTED after query >>>> + */ >>>> + (void)dirtyrate_set_state(&CalculatingState, CalculatingState, >>>> + DIRTY_RATE_STATUS_UNSTARTED); >>> >>> Is there a reason for this restriction? Removing it would require >>> clarifying the state model, I suppose. >>> >> We only support query once for each calculation. >> Otherwise, it could always query dirtyrate, but maybe the dirtyrate is calculated >> long time ago. > > There's nothing in the current interface that prevents this from being > the case already - the caller could initiate a 1 second sample, then > wait 24 hours to query the result. > > Obviously this would generally be regarded as "d'oh - don't do that", > but the same argument would apply if the caller is allowed to query the > results multiple times. > > Perhaps a complete solution would be to include information about the > sample period with the result. The caller could then determine whether > the sample is of adequate quality (sufficiently recent, taken over a > sufficiently long time period) for its' intended use. > You mean add timestamp when i calculate? Actually, I do not want make it complicate for qemu code, maybe it could be left for user to implement both two qmp commands like in libvirt-api. On the other hand, it really bother me that we need to reset calculating state to make sure the state model could be restart in next calculation. For now, i put it after query_dirty_rate_info is finished as you see, it should not be a good idea:( Maybe it is better to initialize at the beginning of qmp_calc_dirty_rate(). > dme. >