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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6bb9c87c487sm26759996d6.131.2024.08.04.08.43.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Aug 2024 08:43:15 -0700 (PDT) Date: Sun, 4 Aug 2024 11:43:13 -0400 From: Peter Xu To: David Hildenbrand Cc: Steve Sistare , qemu-devel@nongnu.org, Fabiano Rosas , Marcel Apfelbaum , Eduardo Habkost , Philippe Mathieu-Daude , Paolo Bonzini , "Daniel P. Berrange" , 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> <37d9e725-1be7-48e1-b621-3f657192f124@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <37d9e725-1be7-48e1-b621-3f657192f124@redhat.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: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.145, 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=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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 Mon, Jul 22, 2024 at 10:59:47AM +0200, David Hildenbrand wrote: > > So I wonder whether there's comparison between exec() and transfer mode > > that you recently proposed. > > > > I'm asking because exec() (besides all the rest of things that I dislike on > > it in this approach..) should be simply slower, logically, due to the > > serialized operation to (1) tearing down the old mm, (2) reload the new > > ELF, then (3) runs through the QEMU init process. > > > > If with a generic migration solution, the dest QEMU can start running (2+3) > > concurrently without even need to run (1). > > I'll note (not sure if already discussed) that with the "async-teardown" > option we have a way to move the MM teardown to a separate process, such > that it will happen asynchronously. I just had a look, maybe it won't trivially work, as it relies on QEMU process to quit first.. async_teardown_fn(): if (the_ppid == getppid()) { pause(); } While if we stick with exec(), then PID shouldn't change, so the teardown process can hold the mm and pause until the VM is destroyed.. Thanks, -- Peter Xu