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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7ae7562d7f7sm485353785a.46.2024.10.09.13.57.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Oct 2024 13:57:34 -0700 (PDT) Date: Wed, 9 Oct 2024 16:57:26 -0400 From: Peter Xu To: Steven Sistare Cc: Fabiano Rosas , qemu-devel@nongnu.org, David Hildenbrand , Marcel Apfelbaum , Eduardo Habkost , Philippe Mathieu-Daude , Paolo Bonzini , "Daniel P. Berrange" , Markus Armbruster Subject: Re: [PATCH V2 13/13] migration: cpr-transfer mode Message-ID: References: <87ed4qtpo1.fsf@suse.de> <877caitno5.fsf@suse.de> <8b92a6ee-19f7-4483-9766-6b849cc04017@oracle.com> <97268719-56f3-4d7f-aa21-c04cd0262601@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <97268719-56f3-4d7f-aa21-c04cd0262601@oracle.com> Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.151, 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, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=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 On Wed, Oct 09, 2024 at 04:18:31PM -0400, Steven Sistare wrote: > Yes, I am also brainstorming along these lines, looking for more gotcha's, > but its a big design change. I don't love it so far. > > These issues all creep in because of transfer mode. Exec mode did not have this > problem, as cpr-state is written to an in-memory file. I understand. Hopefully we're getting there very soon.. I still have concern on having -global used in productions, and meanwhile it might still be challenging for handshake to work as early as cpr stage even for later, because at least in my mind the handshake still happens in the main migration channel (where it includes channel establishments etc, which is not proper during cpr stage). I don't really know whether that'll work at last.. So in my mind the previous two-steps proposal is so far the only one that all seem to work, with no unpredictable side effects. Said that, maybe we can still think about simpler solutions in the following days or see others opinions, we don't need to make a decision today, so maybe there's still better way to go. -- Peter Xu