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 D20ADC4332F for ; Tue, 14 Nov 2023 10:36:02 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r2ql9-000473-6f; Tue, 14 Nov 2023 05:35:07 -0500 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 1r2ql7-00046c-HC for qemu-devel@nongnu.org; Tue, 14 Nov 2023 05:35:05 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r2ql5-00015v-Kk for qemu-devel@nongnu.org; Tue, 14 Nov 2023 05:35:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699958101; 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=iPvaTYp6umAG9oup8+y58bUWGpXJGCojh+MB6c0YdRY=; b=MCEZxY0o7pMG5nJIoBy5X3Y5wRfM0kC1JK36XKL2G8+yeSSRQFzlrFjnSxDI+jQFPWYxKV jkW12YobdeFO+x1vVa5W6CYknfsetViI6zgjnTLCrVCK3cJ0ZdYqr47YRPxxkNpWv/TPs5 q46PB94QznfoG0SpSsStc/z3Lhd7bKc= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-660-Aty8uiaDMxCPm9pOtYjc5A-1; Tue, 14 Nov 2023 05:34:57 -0500 X-MC-Unique: Aty8uiaDMxCPm9pOtYjc5A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5387529AA3A5; Tue, 14 Nov 2023 10:34:57 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.108]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3897036EE; Tue, 14 Nov 2023 10:34:56 +0000 (UTC) Date: Tue, 14 Nov 2023 10:34:54 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Juan Quintela Cc: Markus Armbruster , Peter Xu , qemu-devel@nongnu.org, Fabiano Rosas , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Thomas Huth Subject: Re: Configuring migration Message-ID: References: <878r8ajngg.fsf@pond.sub.org> <875y3dixzp.fsf@pond.sub.org> <8734yhgrzl.fsf@pond.sub.org> <877cnrjd71.fsf@pond.sub.org> <87zfzz82xq.fsf@secure.mitica> <87msvw6xm2.fsf_-_@pond.sub.org> <87pm0cochf.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87pm0cochf.fsf@secure.mitica> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 Received-SPF: pass client-ip=170.10.133.124; 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_H3=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=ham 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 Tue, Nov 14, 2023 at 11:28:28AM +0100, Juan Quintela wrote: > Daniel P. Berrangé wrote: > > On Thu, Nov 02, 2023 at 03:25:25PM +0100, Markus Armbruster wrote: > >> Now let's try to apply this to migration. > >> > >> As long as we can have just one migration, we need just one QAPI object > >> to configure it. > >> > >> We could create the object with -object / object_add. For convenience, > >> we'd probably want to create one with default configuration > >> automatically on demand. > >> > >> We could use qom-set to change configuration. If we're not comfortable > >> with using qom-set for production, we could do something like > >> blockdev-reopen instead. > > > > Do we even need to do this via a QAPI object ? > > > > Why are we not just making the obvious design change of passing everything > > with the 'migrate' / 'migrate-incoming' commands that kick it off: > > > > ie: > > > > { 'command': 'migrate', > > 'data': {'uri': 'str', > > '*channels': [ 'MigrationChannel' ], > > '*capabilities': [ 'MigrateCapability' ], > > '*parameters': [ 'MigrateParameters' ], > > '*detach': 'bool', '*resume': 'bool' } } > > Once that we are doing incompatible changes: This is not incompatible - it is fully backcompatible with existing usage initially, which should make it pretty trivial to introduce to the code. Mgmt apps can carry on using migrate-set-capabilities and migrate-set-parameters, and ignore these new 'capabilities' and 'parameters' fields if desired. Only once we decide to deprecate migrate-set-capabilities, would it become incompatible. > - resume can be another parameter Potentially yes, but 'resume' is conceptually different to all the other capabilities and parameters, so I could see it remaining as a distinct field as it is now > - detach is not needed. QMP don't use it, and HMP don't need to pass it > to qmp_migrate() to make the non-detached implemntation. We could deprecate that today then. > > > > (deprecated bits trimmed for clarity) > > > > and the counterpart: > > > > { 'command': 'migrate-incoming', > > 'data': {'*uri': 'str', > > '*channels': [ 'MigrationChannel' ], > > '*capabilities': [ 'MigrateCapability' ], > > '*parameters': [ 'MigrateParameters' ] } } > > > > such that the design is just like 99% of other commands which take > > all their parameters directly. We already have 'migrate-set-parameters' > > remaining for the runtime tunables, and can deprecate the usage of this > > when migration is not already running, and similarly deprecate > > migrate-set-capabilities. > > This makes sense to me, but once that we change, we could try to merge > capabilities and parameters. See my other email on this topic. > Basically the distition is arbitrary, so just have one of them. > > Or better, as I said in the other email, we have two types of > parameters: > - the ones that need to be set before migration starts > - the ones that can be changed at any time > > So to be simpler, I think that 1st set should be passed to the commands > themselves and the others should only be set with > migrate_set_parameters. As a mgmt app dev I don't want there to be an arbitrary distinction between what I can pass with 'migrate' and what I have to use a separate command for. If I'm starting a migration, I just want to pass all the settings with the 'migrate' command. I should not have to care about separate 'migrate-set-parameters' command at all, unless I actually need to change something on the fly (many migrates will never need this). 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 :|