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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 24E2DC54EE9 for ; Wed, 21 Sep 2022 01:50:05 +0000 (UTC) Received: from localhost ([::1]:53238 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oaosF-0005B6-UY for qemu-devel@archiver.kernel.org; Tue, 20 Sep 2022 21:50:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57620) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oaoqV-0003iL-CF; Tue, 20 Sep 2022 21:48:15 -0400 Received: from m15113.mail.126.com ([220.181.15.113]:59061) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oaoqP-00017L-L4; Tue, 20 Sep 2022 21:48:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=126.com; s=s110527; h=Message-ID:Subject:From:Date:Mime-Version; bh=VSH0r cQJ215pBWJMglHGZwR4ynf5Zp/OT1mXKgo0htM=; b=SiVvkwYLoMJRtEFwp8IRC u19rjdJ1AiQeK56LiDX+GSvSWMBnEgj29mA7FUUMiGF4R0AjJ2U7FpvGurngbLSo CrJL5NK9yciXGeJVK8iDJz6yJCifslkKsbRjFHUtvG8TRKmDbrXn3hqOp46Zdnk+ TVwAP/47sdavlsgfPi6FVA= Received: from localhost.localdomain (unknown [117.160.246.157]) by smtp3 (Coremail) with SMTP id DcmowAAnfMgzbSpjdiHeBw--.2145S3; Wed, 21 Sep 2022 09:47:35 +0800 (CST) Message-ID: Subject: Re: [PATCH] ratelimit: restrict the delay time to a non-negative value From: Wang Liang To: Alberto Garcia , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: pbonzini@redhat.com, stefanha@redhat.com, silbe@linux.vnet.ibm.com, Wang Liang Date: Wed, 21 Sep 2022 09:47:32 +0800 In-Reply-To: References: <20220920123350.205391-1-wangliangzz@126.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-16.el8) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-CM-TRANSID: DcmowAAnfMgzbSpjdiHeBw--.2145S3 X-Coremail-Antispam: 1Uf129KBjvdXoW7XFy3tF4DXFWDtw17Aw1UJrb_yoWfGFg_GF yaq3s5AryjvFn7Cr42y3WIyrn3Jr1rXw48Jr48JrZrJFy8JaykAF1UWw12qFWavF4I9FW5 Gr4Y9397ArWjgjkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7xRiYL95UUUUU== X-Originating-IP: [117.160.246.157] X-CM-SenderInfo: pzdqwzpldqw6b26rjloofrz/1tbiuQ2C1lpD+m1VZAABse Received-SPF: pass client-ip=220.181.15.113; envelope-from=wangliangzz@126.com; helo=m15113.mail.126.com 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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 2022-09-20 at 13:18 +0000, Alberto Garcia wrote: > On Tue 20 Sep 2022 08:33:50 PM +08, wangliangzz@126.com wrote: > > From: Wang Liang > > > > The delay time should never be a negative value. > > > > - return limit->slice_end_time - now; > > + return MAX(limit->slice_end_time - now, 0); > > How can this be negative? slice_end_time is guaranteed to be larger > than > now: > > if (limit->slice_end_time < now) { > /* Previous, possibly extended, time slice finished; reset > the > * accounting. */ > limit->slice_start_time = now; > limit->slice_end_time = now + limit->slice_ns; > limit->dispatched = 0; > } > This is just a guarantee. If slice_end_time is assigned later by limit->slice_end_time = limit->slice_start_time + (uint64_t)(delay_slices * limit->slice_ns); There may be precision issues at that time. > Berto