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 0DFAEC001DB for ; Sat, 5 Aug 2023 08:06:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qSCIU-0000MB-BK; Sat, 05 Aug 2023 04:06:02 -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 1qSCIS-0000DG-PL for qemu-devel@nongnu.org; Sat, 05 Aug 2023 04:06:00 -0400 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 1qSCIR-0007rp-4I for qemu-devel@nongnu.org; Sat, 05 Aug 2023 04:06:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1691222758; 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=cz/AbyB3gR8281UPiOO3llHKXaz6epLpZ/36x6odaDE=; b=aENZ2ZfG74b/V3qFrMcUTnZh2hm9rkd1/uOYEfQnjcd5KPQRFTGG327Aj8ISMkfrjftizW pRwFXJa1K+e487s9AozcZb7RcQo45s/PYvZdQPL8FYRe6Sosqnn5nD/vspGxgnZ2/0KhcB 4eUnG6SuA/9hMCrK2uND6U5f2dN1OMo= Received: from mimecast-mx02.redhat.com (66.187.233.73 [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-672-1kKORC-rOEGvBNcd93WZOg-1; Sat, 05 Aug 2023 04:05:55 -0400 X-MC-Unique: 1kKORC-rOEGvBNcd93WZOg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EB9423C11C7D; Sat, 5 Aug 2023 08:05:54 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.193.50]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A4FF6C5796B; Sat, 5 Aug 2023 08:05:54 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 8459921E692A; Sat, 5 Aug 2023 10:05:53 +0200 (CEST) From: Markus Armbruster To: Peter Xu Cc: Daniel P. =?utf-8?Q?Berrang=C3=A9?= , qemu-devel@nongnu.org, Leonardo Bras Soares Passos , Eric Blake , Juan Quintela , Chensheng Dong , Zhiyi Guo , Fabiano Rosas Subject: Re: [PATCH] migration: Allow user to specify migration available bandwidth References: <20230724170755.1114519-1-peterx@redhat.com> <87351cfdrq.fsf@pond.sub.org> <87o7jz8a6o.fsf@pond.sub.org> Date: Sat, 05 Aug 2023 10:05:53 +0200 In-Reply-To: (Peter Xu's message of "Fri, 4 Aug 2023 10:02:54 -0400") Message-ID: <87a5v5ykv2.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Peter Xu writes: > On Fri, Aug 04, 2023 at 02:39:15PM +0100, Daniel P. Berrang=C3=A9 wrote: >> On Wed, Jul 26, 2023 at 11:12:31AM -0400, Peter Xu wrote: >> > On Wed, Jul 26, 2023 at 08:21:35AM +0200, Markus Armbruster wrote: >> > > Peter Xu writes: >> > >=20 >> > > > Hi, Markus, >> > > > >> > > > On Tue, Jul 25, 2023 at 01:10:01PM +0200, Markus Armbruster wrote: >> > >=20 >> > > [...] >> > >=20 >> > > >> For better or worse, we duplicate full documentation between >> > > >> MigrationParameter, MigrateSetParameters, and MigrationParameters= . This >> > > >> would be the first instance where we reference instead. I'm not = opposed >> > > >> to use references, but if we do, I want them used consistently. >> > > > >> > > > We discussed this over the other "switchover" parameter, but that = patchset >> > > > just stranded.. >> > > > >> > > > Perhaps I just provide a pre-requisite patch to remove all the com= ments in >> > > > MigrateSetParameters and MigrationParameters, letting them all poi= nt to >> > > > MigrationParameter? >> > >=20 >> > > Simplifies maintaining the doc commments. But how does it affect the >> > > documentation generated from it? Better, neutral, or worse? >> >=20 >> > Probably somewhere neutral. There are definitely benefits, shorter >> > >> > man/html page in total, and avoid accidentally different docs over the= same >> > fields. E.g., we sometimes have different wordings for different obje= cts: >> >=20 >> > max-cpu-throttle >> > maximum cpu throttle percentage. Defaults to 99. (Sinc= e 3.1) >> >=20 >> > max-cpu-throttle: int (optional) >> > maximum cpu throttle percentage. The default value is 9= 9. (Since 3.1) >> >=20 >> > This one is fine, but it's just very easy to leak in something that sh= ows >> > differently. It's good to provide coherent documentation for the same >> > fields over all three objects. >>=20 >> Do we have any actual problems though where the difference in >> docs is actively harmful ? I agree there's a possbility of the >> duplication being problematic, but unless its actually the >> case in reality, it is merely a theoretical downside. >>=20 >> IMHO for someone consuming the docs, this patch is worse, not neutral. > > I agree. > >>=20 >> >=20 >> > When looking at qemu-qmp-ref.7, it can be like this when we can invite= the >> > reader to read the other section (assuming we only keep MigrationParam= eter >> > to keep the documentations): >> >=20 >> > MigrationParameters (Object) >> >=20 >> > The object structure to represent a list of migration parameter= s. >> > The optional members aren't actually optional. For detailed >> > explanation for each of the field, please refer to the document= ation >> > of MigrationParameter. >> >=20 >> > But the problem is we always will generate the Members entry, where now >> > it'll all filled up with "Not documented".. >> >=20 >> > Members >> > announce-initial: int (optional) >> > Not documented >> >=20 >> > announce-max: int (optional) >> > Not documented >> >=20 >> > announce-rounds: int (optional) >> > Not documented >> >=20 >> > [...] >> >=20 >> > I think maybe it's better we just list the members without showing "Not >> > documented" every time for the other two objects. Not sure whether it= 's an >> > easy way to fix it, or is it a major issue. >> >=20 >> > For developers, dedup the comment should always be a win, afaict. >>=20 >> IMHO that's optimizing for the wrong people and isn't a measurable >> win anyway. Someone adding a new parameter can just cut+paste the >> same docs string in the three places. It is a cost, but it is a >> small one time cost, where having "not documented" is a ongoing >> cost for consumers of our API. >>=20 >> I don't think the burden on QEMU maintainers adding new migration >> parameters is significant enough to justify ripping out our existing >> docs. > > I had that strong feeling mostly because I'm a migration developer and > migration reviewer, so I suffer on both sides. :) I was trying to stand o= ut > for either any future author/reviewer from that pov, but I think indeed t= he > ultimate consumer is the reader. > > Fundamentally to solve the problem, maybe we must dedup the objects rather > than the documents only? I'll try to dig a bit more in this area next we= ek > if I have time, any link for previous context would be welcomed (or obvio= us > reason that we just won't be able to do that; I only know that at least > shouldn't be trivial to resolve). > > For this one - Markus, let me know what do you think, or I'll simply repo= st > v3 with the duplications (when needed, probably later not sooner). Since you want to investigate de-duplicating the objects, do that *first*. If you succeed, we don't have to argue about de-duplicating docs.