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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-46c873216dbsm64307791cf.7.2025.01.15.04.55.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jan 2025 04:55:14 -0800 (PST) Date: Wed, 15 Jan 2025 07:55:13 -0500 From: Peter Xu To: Jiri Denemark Cc: qemu-devel@nongnu.org, Juraj Marcin , Julia Suvorova , Prasad Pandit , Fabiano Rosas Subject: Re: [PATCH 00/16] migration: Switchover phase refactoring Message-ID: References: <20250114230746.3268797-1-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -39 X-Spam_score: -4.0 X-Spam_bar: ---- X-Spam_report: (-4.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.141, 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_H2=-1.793, 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, Jan 15, 2025 at 10:12:45AM +0100, Jiri Denemark wrote: > On Tue, Jan 14, 2025 at 18:07:30 -0500, Peter Xu wrote: > > CI: https://gitlab.com/peterx/qemu/-/pipelines/1625266692 > > (note: warning is present on rust stuff, but shouldn't be relevant) > > > > This series refactors the migration switchover path quite a bit. I started > > this work initially to measure the JSON writer overhead, but then I decided > > to cleanup the switchover path in general when I am at it altogether, as I > > wanted to do this for a long time. > > > > A few major things I tried to do: > > > ... > > - DEVICE migration state > > > > QEMU has a very special DEVICE migration state, that only happens with > > precopy, and only when pause-before-switchover capability is enabled. > > Due to that specialty we can't merge precopy and postcopy code on > > switchover starts, because the state machine will be different. > > > > However after I checked the history and also with libvirt developers, > > this seems unnecessary. So I had one patch making DEVICE state to be > > the "switchover" phase for precopy/postcopy unconditionally. That will > > make the state machine much easier for both modes, meanwhile nothing is > > expected to break with it (but please still shoot if anyone knows / > > suspect something will, or could, break..). > > No problem from libvirt side... > > Tested-by: Jiri Denemark This is definitely reassuring.. thanks a lot, Jiri! -- Peter Xu