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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 6640BC3A5A7 for ; Wed, 4 Sep 2019 15:44:23 +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 3877E22CEA for ; Wed, 4 Sep 2019 15:44:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3877E22CEA 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]:34626 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i5XSI-0005Rs-6s for qemu-devel@archiver.kernel.org; Wed, 04 Sep 2019 11:44:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34064) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i5XQb-0004XC-E8 for qemu-devel@nongnu.org; Wed, 04 Sep 2019 11:42:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i5XQa-0000wq-AT for qemu-devel@nongnu.org; Wed, 04 Sep 2019 11:42:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35977) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i5XQW-0000tG-C7; Wed, 04 Sep 2019 11:42:32 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0801E307D868; Wed, 4 Sep 2019 15:42:31 +0000 (UTC) Received: from [10.3.116.234] (ovpn-116-234.phx2.redhat.com [10.3.116.234]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B5BB35D9C9; Wed, 4 Sep 2019 15:42:29 +0000 (UTC) To: Denis Plotnikov , armbru@redhat.com, qemu-devel@nongnu.org References: <20190904152915.30755-1-dplotnikov@virtuozzo.com> <20190904152915.30755-2-dplotnikov@virtuozzo.com> From: Eric Blake Openpgp: preference=signencrypt Autocrypt: addr=eblake@redhat.com; keydata= xsBNBEvHyWwBCACw7DwsQIh0kAbUXyqhfiKAKOTVu6OiMGffw2w90Ggrp4bdVKmCaEXlrVLU xphBM8mb+wsFkU+pq9YR621WXo9REYVIl0FxKeQo9dyQBZ/XvmUMka4NOmHtFg74nvkpJFCD TUNzmqfcjdKhfFV0d7P/ixKQeZr2WP1xMcjmAQY5YvQ2lUoHP43m8TtpB1LkjyYBCodd+LkV GmCx2Bop1LSblbvbrOm2bKpZdBPjncRNob73eTpIXEutvEaHH72LzpzksfcKM+M18cyRH+nP sAd98xIbVjm3Jm4k4d5oQyE2HwOur+trk2EcxTgdp17QapuWPwMfhaNq3runaX7x34zhABEB AAHNHkVyaWMgQmxha2UgPGVibGFrZUByZWRoYXQuY29tPsLAegQTAQgAJAIbAwULCQgHAwUV CgkICwUWAgMBAAIeAQIXgAUCS8fL9QIZAQAKCRCnoWtKJSdDahBHCACbl/5FGkUqJ89GAjeX RjpAeJtdKhujir0iS4CMSIng7fCiGZ0fNJCpL5RpViSo03Q7l37ss+No+dJI8KtAp6ID+PMz wTJe5Egtv/KGUKSDvOLYJ9WIIbftEObekP+GBpWP2+KbpADsc7EsNd70sYxExD3liwVJYqLc Rw7so1PEIFp+Ni9A1DrBR5NaJBnno2PHzHPTS9nmZVYm/4I32qkLXOcdX0XElO8VPDoVobG6 gELf4v/vIImdmxLh/w5WctUpBhWWIfQDvSOW2VZDOihm7pzhQodr3QP/GDLfpK6wI7exeu3P pfPtqwa06s1pae3ad13mZGzkBdNKs1HEm8x6zsBNBEvHyWwBCADGkMFzFjmmyqAEn5D+Mt4P zPdO8NatsDw8Qit3Rmzu+kUygxyYbz52ZO40WUu7EgQ5kDTOeRPnTOd7awWDQcl1gGBXgrkR pAlQ0l0ReO57Q0eglFydLMi5bkwYhfY+TwDPMh3aOP5qBXkm4qIYSsxb8A+i00P72AqFb9Q7 3weG/flxSPApLYQE5qWGSXjOkXJv42NGS6o6gd4RmD6Ap5e8ACo1lSMPfTpGzXlt4aRkBfvb NCfNsQikLZzFYDLbQgKBA33BDeV6vNJ9Cj0SgEGOkYyed4I6AbU0kIy1hHAm1r6+sAnEdIKj cHi3xWH/UPrZW5flM8Kqo14OTDkI9EtlABEBAAHCwF8EGAEIAAkFAkvHyWwCGwwACgkQp6Fr SiUnQ2q03wgAmRFGDeXzc58NX0NrDijUu0zx3Lns/qZ9VrkSWbNZBFjpWKaeL1fdVeE4TDGm I5mRRIsStjQzc2R9b+2VBUhlAqY1nAiBDv0Qnt+9cLiuEICeUwlyl42YdwpmY0ELcy5+u6wz mK/jxrYOpzXKDwLq5k4X+hmGuSNWWAN3gHiJqmJZPkhFPUIozZUCeEc76pS/IUN72NfprZmF Dp6/QDjDFtfS39bHSWXKVZUbqaMPqlj/z6Ugk027/3GUjHHr8WkeL1ezWepYDY7WSoXwfoAL 2UXYsMAr/uUncSKlfjvArhsej0S4zbqim2ZY6S8aRWw94J3bSvJR+Nwbs34GPTD4Pg== Organization: Red Hat, Inc. Message-ID: Date: Wed, 4 Sep 2019 10:42:28 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190904152915.30755-2-dplotnikov@virtuozzo.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="e18TxEGla0bKvIh5fSsQcZ5J8wVTTclP3" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Wed, 04 Sep 2019 15:42:31 +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 v5 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, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --e18TxEGla0bKvIh5fSsQcZ5J8wVTTclP3 Content-Type: multipart/mixed; boundary="cMzMBBmc2n3JwEyKHbkxNGtGheHfP99nW"; protected-headers="v1" From: Eric Blake To: Denis Plotnikov , armbru@redhat.com, qemu-devel@nongnu.org Cc: kwolf@redhat.com, mreitz@redhat.com, den@virtuozzo.com, vsementsov@virtuozzo.com, qemu-block@nongnu.org Message-ID: Subject: Re: [PATCH v5 1/3] qcow2: introduce compression type feature References: <20190904152915.30755-1-dplotnikov@virtuozzo.com> <20190904152915.30755-2-dplotnikov@virtuozzo.com> In-Reply-To: <20190904152915.30755-2-dplotnikov@virtuozzo.com> --cMzMBBmc2n3JwEyKHbkxNGtGheHfP99nW Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 9/4/19 10:29 AM, Denis Plotnikov wrote: > 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. >=20 > It is implied that the compression type is set on the image creation an= d > can be changed only later by image conversion, thus compression type > defines the only compression algorithm used for the image. >=20 > The goal of the feature is to add support of other compression algorith= ms > 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 provides a performance advantage in backup scenarios. >=20 > The default compression is ZLIB. Images created with ZLIB compression t= ype > are backward compatible with older qemu versions. >=20 > Signed-off-by: Denis Plotnikov > --- > +++ b/docs/interop/qcow2.txt > @@ -165,6 +170,18 @@ in the description of a field. > Length of the header structure in bytes. For versi= on 2 > images, the length is always assumed to be 72 byte= s. > =20 > + 104 - 107: compression_type > + Defines the compression method used for compressed= clusters. > + A single compression type is applied to all compre= ssed image > + clusters. > + The compression type is set on image creation only= =2E This sentence adds nothing for me; you could delete it, and the spec would still be just as useful (and less questionable about whether I can 'qemu-img amend' an image to use a different compression type in-place by rewriting all existing compressed clusters). With or without that sentence, Reviewed-by: Eric Blake --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --cMzMBBmc2n3JwEyKHbkxNGtGheHfP99nW-- --e18TxEGla0bKvIh5fSsQcZ5J8wVTTclP3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAl1v22QACgkQp6FrSiUn Q2qT1Af+NbaYsqsj1QJ0+DkrKZLHnlqP6Hx00qcQZg1SkA+2tEdI+VTAi47Kgo5s hARR3Ox0QmpjNIekwRmJRxoKTWbNuaLytUoQEMCl1vU9uwEVkHCPPZkMciRQK4RN /Y8MSrNBiv0JxlZ7lewmF3Fz78fDgjobZOeHYX1ZPBJ1fHMiErnfhNPh2ghFsSEu 0ZcjQf8MhbVa4yAUgpMhCi3Im6HJ683xeIcqMyyzA1GwysClHgerBigOtcqfoIdy FAmYRv8MVV1x2uxdWphKWZ1TDH27XBispNFpJz70L1/XgekDF7FaWZBY6rYbnZ+e 84017g1P8F6jSjjrOknl4xYWe+bLqA== =hkak -----END PGP SIGNATURE----- --e18TxEGla0bKvIh5fSsQcZ5J8wVTTclP3--