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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 30BC1EB64D7 for ; Fri, 23 Jun 2023 08:24:15 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qCc5N-0005fI-Pe; Fri, 23 Jun 2023 04:24:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qCc4z-0005QT-KF for qemu-devel@nongnu.org; Fri, 23 Jun 2023 04:23:42 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qCc4w-0004DK-MB for qemu-devel@nongnu.org; Fri, 23 Jun 2023 04:23:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1687508610; h=from:from:reply-to: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=pwHcrJZXSxKxPAwkBxU6V5vd99z4gjJbODpHGUgLUpA=; b=bbbMmxtm8NkXCt8rhUgS20ylTM4ur87/84jsZLVeryftM6t82vUfXv5Z5YAKJOthvda70e WOityHSH5grmANOGgiE1RUnHtAsndpwVadjni0ezNsuYRrEvRd83q+hir47VDEaBG6G0LS yt2jEdMhrLm7T4eVOTcNsoJShJnNk5o= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-513-8shDqJzwPgqYMDQo4bFPZQ-1; Fri, 23 Jun 2023 04:23:22 -0400 X-MC-Unique: 8shDqJzwPgqYMDQo4bFPZQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 52F2A90ED25; Fri, 23 Jun 2023 08:23:22 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.44]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9F2BF1121314; Fri, 23 Jun 2023 08:23:20 +0000 (UTC) Date: Fri, 23 Jun 2023 09:23:18 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Peter Xu Cc: Juan Quintela , Paolo Bonzini , qemu-devel@nongnu.org, Markus Armbruster , Leonardo Bras , qemu-block@nongnu.org, Stefan Hajnoczi , Eric Blake , Fam Zheng , Thomas Huth , libvir-list@redhat.com Subject: Re: [RFC 4/6] migration: Deprecate -incoming Message-ID: References: <20230612193344.3796-1-quintela@redhat.com> <20230612193344.3796-5-quintela@redhat.com> <875y7sflqb.fsf@secure.mitica> <87wmzv7ubn.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Jun 22, 2023 at 11:54:43AM -0400, Peter Xu wrote: > On Thu, Jun 22, 2023 at 10:59:58AM +0100, Daniel P. Berrangé wrote: > > I've mentioned several times before that the user should never need to > > set this multifd-channels parameter (nor many other parameters) on the > > destination in the first place. > > > > The QEMU migration stream should be changed to add a full > > bi-directional handshake, with negotiation of most parameters. > > IOW, the src QEMU should be configured with 16 channels, and > > it should connect the primary control channel, and then directly > > tell the dest that it wants to use 16 multifd channels. > > > > If we're expecting the user to pass this info across to the dest > > manually we've already spectacularly failed wrt user friendliness. > > I can try to move the todo even higher. Trying to list the initial goals > here: > > - One extra phase of handshake between src/dst (maybe the time to boost > QEMU_VM_FILE_VERSION) before anything else happens. > > - Dest shouldn't need to apply any cap/param, it should get all from src. > Dest still need to be setup with an URI and that should be all it needs. There are a few that the dest will still need set explicitly. Specifically the TLS parameters - tls-authz and tls-creds, because those are both related to --object parameters configured on the dst QEMU. Potentially there's an argument to be made for the TLS parameters to be part fo the initial 'migrate' and 'migrate-incoming' command data, as they're specifically related to the connection establishment, while (most) of the other params are related to the migration protocol running inside the connection. A few other parameters are also related to the connection establishment, most notably the enablement multifd, postcopy and postcopy-pre-empt. I think with those ones we don't need to set them on the src either. With the new migration handshake we should probably use multifd codepaths unconditionally, with a single channel. By matching with the introduction of new protocol, we have a nice point against which to deprecate the old non-multifd codepaths. We'll need to keep the non-multifd code around *alot* longer than the normal deprecation cycle though, as we need mig to/from very old QEMUs. The enablement of postcopy could be automatic too - src & dst can both detect if their host OS supports it. That would make all migrations post-copy capable. The mgmt app just needs to trigger the switch to post-copy mode *if* they want to use it. Likewise we can just always assume postcopy-pre-empt is available. I think 'return-path' becomes another one we can just assume too. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|