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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 96EF0C2D0CE for ; Fri, 24 Jan 2020 05:45:56 +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 600B92070A for ; Fri, 24 Jan 2020 05:45:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VeuFMUha" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 600B92070A 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]:37714 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iurn1-0008Uw-Iq for qemu-devel@archiver.kernel.org; Fri, 24 Jan 2020 00:45:55 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:53040) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iurmN-0007wg-3C for qemu-devel@nongnu.org; Fri, 24 Jan 2020 00:45:16 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iurmL-0001BT-8B for qemu-devel@nongnu.org; Fri, 24 Jan 2020 00:45:14 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:46531 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iurmK-00019E-PV for qemu-devel@nongnu.org; Fri, 24 Jan 2020 00:45:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579844711; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SPfhegMhVYtp7WdGZ7ghk+OtJa7mGpszbakQi+yQBh4=; b=VeuFMUhaC+QWdvIwnteQq2Lo73ScYrzSVNA7WV1+PuaXdQfrPCYJXJuAcYK9Y4XoLgrRoF Q6HHzzLHfwBvQ8g7hhl3SQrg2hR8vseCIq/jdkTNu8qw2MDydYJzoQBtKBTltGt+50uAZy 6MRLVQV8WQkRedSccj3LGTlfTDqmmt8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-4-mBVfPiosNsW5h9-sCZvjiA-1; Fri, 24 Jan 2020 00:45:06 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C9B4810054E3; Fri, 24 Jan 2020 05:45:05 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-116-131.ams2.redhat.com [10.36.116.131]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 73BA185790; Fri, 24 Jan 2020 05:45:05 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id DCF271138600; Fri, 24 Jan 2020 06:45:03 +0100 (CET) From: Markus Armbruster To: "Richard W.M. Jones" Subject: Re: qemu-img convert vs writing another copy tool References: <20200123183500.GA27166@redhat.com> <20200123191709.GM3888@redhat.com> Date: Fri, 24 Jan 2020 06:45:03 +0100 In-Reply-To: <20200123191709.GM3888@redhat.com> (Richard W. M. Jones's message of "Thu, 23 Jan 2020 19:17:09 +0000") Message-ID: <875zh15rxc.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: mBVfPiosNsW5h9-sCZvjiA-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 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: berrange@redhat.com, qemu-block@nongnu.org, qemu-devel@nongnu.org, ptoscano@redhat.com, mkletzan@redhat.com, marnold@redhat.com, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" "Richard W.M. Jones" writes: > On Thu, Jan 23, 2020 at 07:53:57PM +0100, Max Reitz wrote: >> On 23.01.20 19:35, Richard W.M. Jones wrote: >> > - NBD multi-conn. In my tests this makes a really massive >> > performance difference in certain situations. Again, virt-v2v has >> > a lot of information that we cannot pass to qemu: we know, for >> > example, exactly if the server supports the feature, how many >> > threads are available, in some situations even have information >> > about the network and backing disks that the data will travel over >> > / be stored on. >>=20 >> As far as I understand it, you use qemu-img convert with an NBD source >> or target, too? > > Virt-v2v has many modes, but yes generally there will be either an NBD > source & target, or an NBD source to a local file target. > >> I suppose it=E2=80=99s always easier to let a specialized and freshly wr= itten >> tool handle such information. But it sounds like if such information is >> useful and makes that big of a difference, then it would be good to be >> able to specify it to qemu=E2=80=99s NBD block driver, too. > > qemu-img convert has worked really well for us, and I'm actually _not_ > confident that I could do better with a specialized tool. But there's > definitely more info we could pass, such as the amount of parallelism > we believe is available in the NBD server / processors / disks. > >> > - Machine-parsable progress bars. You can, sort of, parse the >> > progress bar from qemu-img convert, but it's not as easy as it >> > could be. In particular it would be nice if the format was treated >> > as ABI, and if there was a way to have the tool write the progress >> > bar info to a precreated file descriptor. >>=20 >> It doesn=E2=80=99t seem impossible to add this feature to qemu-img, alth= ough I >> wonder about the interface. I suppose we could make it an alternative >> progress output mode (with some command-line flag), and then the >> information would be emitted to stdout (just like the existing progress >> report). You can of course redirect stdout to whatever fd you=E2=80=99d= like, >> so I don=E2=80=99t know whether qemu-img itself needs that specific capa= bility. >>=20 >> OTOH, if you need this feature, why not just use qemu itself? That is, >> a mirror or a backup block job in an otherwise empty VM. > > I don't think we've really thought before about this approach. Maybe > the launching of a VM (even an empty / stopped one) could be a > problem. I guess this is what the new tool that was recently proposed > upstream might help with? (Was it called qemu-block-storage? I can't > find it right this minute) Subject: [RFC PATCH 00/18] Add qemu-storage-daemon To: qemu-block@nongnu.org Date: Thu, 17 Oct 2019 15:01:46 +0200 Message-Id: <20191017130204.16131-1-kwolf@redhat.com> [...]