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=-5.3 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 F0553C4338F for ; Tue, 3 Aug 2021 01:55:17 +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 15C3B60F41 for ; Tue, 3 Aug 2021 01:55:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 15C3B60F41 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:51552 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mAjeD-0005B0-Tk for qemu-devel@archiver.kernel.org; Mon, 02 Aug 2021 21:55:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38856) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mAjdO-0004M3-5k; Mon, 02 Aug 2021 21:54:22 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:2507) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mAjdL-0000TM-Cz; Mon, 02 Aug 2021 21:54:21 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GdybG48vWzYkbL; Tue, 3 Aug 2021 09:54:02 +0800 (CST) Received: from dggpemm500017.china.huawei.com (7.185.36.178) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 3 Aug 2021 09:53:50 +0800 Received: from [10.174.185.76] (10.174.185.76) by dggpemm500017.china.huawei.com (7.185.36.178) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 3 Aug 2021 09:53:50 +0800 Subject: Re: [Question] qemu-img convert block alignment From: Zhenyu Ye To: Kevin Wolf , , , , References: Message-ID: Date: Tue, 3 Aug 2021 09:53:38 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.185.76] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500017.china.huawei.com (7.185.36.178) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=45.249.212.187; envelope-from=yezhenyu2@huawei.com; helo=szxga01-in.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H4=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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" ping? On 2021/4/2 11:52, Zhenyu Ye wrote: > Hi all, > > commit 8dcd3c9b91 ("qemu-img: align result of is_allocated_sectors") > introduces block alignment when doing qemu-img convert. However, the > alignment is: > > s.alignment = MAX(pow2floor(s.min_sparse), > DIV_ROUND_UP(out_bs->bl.request_alignment, > BDRV_SECTOR_SIZE)); > > (where the default s.min_sparse is 8) > When the target device's bl.request_alignment is smaller than 4K, this > will cause additional write-zero overhead and makes the size of target > file larger. > > Is this as expected? Should we change the MAX() to MIN()? > > > Thanks, > zhenyu >