[{"id":1776625,"web_url":"http://patchwork.ozlabs.org/comment/1776625/","msgid":"<88ce047a-c351-6b5b-4dac-3cc6fb07f02e@redhat.com>","list_archive_url":null,"date":"2017-09-27T21:16:09","subject":"Re: [Qemu-devel] [PATCH v4 15/23] qemu-img: Add find_nonzero()","submitter":{"id":64343,"url":"http://patchwork.ozlabs.org/api/people/64343/","name":"John Snow","email":"jsnow@redhat.com"},"content":"On 09/13/2017 12:03 PM, Eric Blake wrote:\n> During 'qemu-img compare', when we are checking that an allocated\n> portion of one file is all zeros, we don't need to waste time\n> computing how many additional sectors after the first non-zero\n> byte are also non-zero. Create a new helper find_nonzero() to do\n> the check for a first non-zero sector, and rebase\n> check_empty_sectors() to use it.\n> \n> The new interface intentionally uses bytes in its interface, even\n> though it still crawls the buffer a sector at a time; it is robust\n> to a partial sector at the end of the buffer.\n> \n> Signed-off-by: Eric Blake \n\nReviewed-by: John Snow ","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; helo=lists.gnu.org;\n\tenvelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n\treceiver=)","ext-mx06.extmail.prod.ext.phx2.redhat.com;\n\tdmarc=none (p=none dis=none) header.from=redhat.com","ext-mx06.extmail.prod.ext.phx2.redhat.com;\n\tspf=fail smtp.mailfrom=jsnow@redhat.com"],"Received":["from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11])\n\t(using TLSv1 with cipher AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3y2Vxj61XJz9t39\n\tfor ;\n\tThu, 28 Sep 2017 07:16:41 +1000 (AEST)","from localhost ([::1]:56380 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t)\n\tid 1dxJh9-0002nv-Vd\n\tfor incoming@patchwork.ozlabs.org; Wed, 27 Sep 2017 17:16:40 -0400","from eggs.gnu.org ([2001:4830:134:3::10]:40440)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from ) id 1dxJgo-0002lU-Hw\n\tfor qemu-devel@nongnu.org; Wed, 27 Sep 2017 17:16:19 -0400","from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from ) id 1dxJgn-0006gz-MT\n\tfor qemu-devel@nongnu.org; Wed, 27 Sep 2017 17:16:18 -0400","from mx1.redhat.com ([209.132.183.28]:44426)\n\tby eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from )\n\tid 1dxJgj-0006g6-DT; Wed, 27 Sep 2017 17:16:13 -0400","from smtp.corp.redhat.com\n\t(int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16])\n\t(using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby mx1.redhat.com (Postfix) with ESMTPS id 7FB7B6371B;\n\tWed, 27 Sep 2017 21:16:12 +0000 (UTC)","from [10.10.121.69] (ovpn-121-69.rdu2.redhat.com [10.10.121.69])\n\tby smtp.corp.redhat.com (Postfix) with ESMTP id E1E208C7D7;\n\tWed, 27 Sep 2017 21:16:09 +0000 (UTC)"],"DMARC-Filter":"OpenDMARC Filter v1.3.2 mx1.redhat.com 7FB7B6371B","To":"Eric Blake , qemu-devel@nongnu.org","References":"<20170913160333.23622-1-eblake@redhat.com>\n\t<20170913160333.23622-16-eblake@redhat.com>","From":"John Snow ","Message-ID":"<88ce047a-c351-6b5b-4dac-3cc6fb07f02e@redhat.com>","Date":"Wed, 27 Sep 2017 17:16:09 -0400","User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101\n\tThunderbird/52.3.0","MIME-Version":"1.0","In-Reply-To":"<20170913160333.23622-16-eblake@redhat.com>","Content-Type":"text/plain; charset=utf-8","Content-Language":"en-US","Content-Transfer-Encoding":"7bit","X-Scanned-By":"MIMEDefang 2.79 on 10.5.11.16","X-Greylist":"Sender IP whitelisted, not delayed by milter-greylist-4.5.16\n\t(mx1.redhat.com [10.5.110.30]);\n\tWed, 27 Sep 2017 21:16:12 +0000 (UTC)","X-detected-operating-system":"by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic]\n\t[fuzzy]","X-Received-From":"209.132.183.28","Subject":"Re: [Qemu-devel] [PATCH v4 15/23] qemu-img: Add find_nonzero()","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"kwolf@redhat.com, famz@redhat.com, qemu-block@nongnu.org,\n\tMax Reitz ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"}}]