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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4531c1c532asm35029581cf.30.2024.08.13.12.46.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Aug 2024 12:46:11 -0700 (PDT) Date: Tue, 13 Aug 2024 15:46:09 -0400 From: Peter Xu To: Steven Sistare Cc: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= , qemu-devel@nongnu.org, Fabiano Rosas , David Hildenbrand , Marcel Apfelbaum , Eduardo Habkost , Philippe Mathieu-Daude , Paolo Bonzini , Markus Armbruster Subject: Re: [PATCH V2 00/11] Live update: cpr-exec Message-ID: References: <1719776434-435013-1-git-send-email-steven.sistare@oracle.com> <5776f6b4-c55f-4e56-aac5-bee7e441ad15@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5776f6b4-c55f-4e56-aac5-bee7e441ad15@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=-0.125, 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: , 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, Aug 06, 2024 at 04:56:18PM -0400, Steven Sistare wrote: > > The flipside, however, is that localhost migration via 2 separate QEMU > > processes has issues where both QEMUs want to be opening the very same > > file, and only 1 of them can ever have them open. I thought we used to have similar issue with block devices, but I assume it's solved for years (and whoever owns it will take proper file lock, IIRC, and QEMU migration should properly serialize the time window on who's going to take the file lock). Maybe this is about something else? > > Indeed, and "files" includes unix domain sockets. Network ports also conflict. > cpr-exec avoids such problems, and is one of the advantages of the method that > I forgot to promote. I was thinking that's fine, as the host ports should be the backend of the VM ports only anyway so they don't need to be identical on both sides? IOW, my understanding is it's the guest IP/ports/... which should still be stable across migrations, where the host ports can be different as long as the host ports can forward guest port messages correctly? Thanks, -- Peter Xu