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=-0.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 B3166C54FD0 for ; Fri, 24 Apr 2020 18:42:17 +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 755EC20774 for ; Fri, 24 Apr 2020 18:42:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="ps+G3tC6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 755EC20774 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=igalia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:48282 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jS3HE-0003Pd-KD for qemu-devel@archiver.kernel.org; Fri, 24 Apr 2020 14:42:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42806) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jS3GJ-0002AR-Bp for qemu-devel@nongnu.org; Fri, 24 Apr 2020 14:41:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.90_1) (envelope-from ) id 1jS3GI-0003O0-R5 for qemu-devel@nongnu.org; Fri, 24 Apr 2020 14:41:19 -0400 Received: from fanzine.igalia.com ([178.60.130.6]:36255) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jS3GI-0003KK-9W; Fri, 24 Apr 2020 14:41:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Type:MIME-Version:Message-ID:Date:References:In-Reply-To:Subject:Cc:To:From; bh=OqaxqUTc753QtjLloI/nimYGhMIk7My7mLj3f13xTcA=; b=ps+G3tC6UozSNQU9c6nWdcFuSLXOEljFYoC3rsz6w7NlfPhNxj/hmpHpt7XmIC76PNOOJa8U7TXuqgAgoSiEap/AGboJ2Pg8YNysgqLyMMf//o3v85/6Ugl2qlXZBhqrxblxRN4WtHfGeZhJJNT74cllsSWbONWnUD0peuWMjZj0yHGm8sXBno8yE8xgr/ySH+FqL/drdzLYpGkOWKClhqxTnBQExEUkKjEXgv54ZCsvUwlhPoG+Fwb5HgYnecx5g2y4Ii8ZkmMWu0Gzn364jmcfGHWFBZD3Kp6SVMx6Zv1xP+MCAYe7dv+LfQ1wqySiZ4bXPSW7ZVvGtOeSb0IH9A==; Received: from maestria.local.igalia.com ([192.168.10.14] helo=mail.igalia.com) by fanzine.igalia.com with esmtps (Cipher TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim) id 1jS3GD-0003ur-AT; Fri, 24 Apr 2020 20:41:13 +0200 Received: from berto by mail.igalia.com with local (Exim) id 1jS3GD-0008H6-0u; Fri, 24 Apr 2020 20:41:13 +0200 From: Alberto Garcia To: Vladimir Sementsov-Ogievskiy , Eric Blake , qemu-devel@nongnu.org Subject: Re: [PATCH v4 24/30] qcow2: Clear the L2 bitmap when allocating a compressed cluster In-Reply-To: <971a6e4b-ba44-4280-89fa-d454cddf12e1@virtuozzo.com> References: <6d596d82ed62615a8565b661691a06bfaf32237e.1584468723.git.berto@igalia.com> <1606ecb5-98ea-fefb-bb98-2ecda1d65f5c@redhat.com> <57ac1a2f-1632-1a00-b18d-1fc2169175b6@redhat.com> <971a6e4b-ba44-4280-89fa-d454cddf12e1@virtuozzo.com> User-Agent: Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) Date: Fri, 24 Apr 2020 20:41:12 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=178.60.130.6; envelope-from=berto@igalia.com; helo=fanzine.igalia.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/24 13:02:51 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x (no timestamps) [generic] [fuzzy] X-Received-From: 178.60.130.6 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: Kevin Wolf , "Denis V . Lunev" , Anton Nefedov , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri 24 Apr 2020 08:15:04 PM CEST, Vladimir Sementsov-Ogievskiy wrote: > AFAIK, now compressed clusters can't be used in scenarios with guest, > as qcow2 driver doesn't support rewriting them. You can write to those images just fine, it's just not efficient because you have to COW the compressed clusters. > Or am I wrong? And we normally don't combine normal and compressed > clusters together in one image. As soon as you start writing to an image with compressed clusters you'll have a combination of both. But it's true that you don't have an image with compressed clusters if what you're looking for is performance. So I wouldn't add support for this if it complicates things too much. Berto