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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 03D9BC606B0 for ; Tue, 9 Jul 2019 06:16:54 +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 CEF8221537 for ; Tue, 9 Jul 2019 06:16:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CEF8221537 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47034 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hkjQq-00022H-Vq for qemu-devel@archiver.kernel.org; Tue, 09 Jul 2019 02:16:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58055) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hkjPc-0001Ye-Ts for qemu-devel@nongnu.org; Tue, 09 Jul 2019 02:15:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hkjPa-0003lj-Um for qemu-devel@nongnu.org; Tue, 09 Jul 2019 02:15:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58236) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hkjPW-0003Yx-Nu; Tue, 09 Jul 2019 02:15:31 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9ABB0307D88C; Tue, 9 Jul 2019 06:15:13 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-116-111.ams2.redhat.com [10.36.116.111]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 09F8A5C5FC; Tue, 9 Jul 2019 06:15:12 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 8EAD91138648; Tue, 9 Jul 2019 08:15:10 +0200 (CEST) From: Markus Armbruster To: Denis Plotnikov References: <20190704130949.14017-1-dplotnikov@virtuozzo.com> <20190704130949.14017-2-dplotnikov@virtuozzo.com> Date: Tue, 09 Jul 2019 08:15:10 +0200 In-Reply-To: <20190704130949.14017-2-dplotnikov@virtuozzo.com> (Denis Plotnikov's message of "Thu, 4 Jul 2019 16:09:47 +0300") Message-ID: <87ef2zag41.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Tue, 09 Jul 2019 06:15:14 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v2 1/3] qcow2: introduce compression type feature 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: kwolf@redhat.com, vsementsov@virtuozzo.com, den@virtuozzo.com, qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Denis Plotnikov writes: > The patch adds some preparation parts for incompatible compression type > feature to QCOW2 header that indicates that *all* compressed clusters > must be (de)compressed using a certain compression type. > > It is implied that the compression type is set on the image creation and > can be changed only later by image conversion, thus compression type > defines the only compression algorithm used for the image. > > The goal of the feature is to add support of other compression algorithms > to qcow2. For example, ZSTD which is more effective on compression than ZLIB. > It works roughly 2x faster than ZLIB providing a comparable compression ratio > and therefore provide a performance advantage in backup scenarios. > > The default compression is ZLIB. Images created with ZLIB compression type > are backward compatible with older qemu versions. > > Signed-off-by: Denis Plotnikov QAPI schema Acked-by: Markus Armbruster