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envelope-from=peterx@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_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-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: qemu development 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 Fri, Jan 30, 2026 at 01:49:42PM +0100, Lukas Straub wrote: > On Tue, 27 Jan 2026 15:38:55 -0500 > Peter Xu wrote: > > > On Sun, Jan 25, 2026 at 09:40:10PM +0100, Lukas Straub wrote: > > > With colo we load device vmstate during each checkpoint, on top of > > > a vm that was already running. Some devices expect a reset before > > > loading vmstate on such a previously running vm. > > > > > > This fixes a crash when using COLO with Q35 machine. > > > > > > Signed-off-by: Lukas Straub > > > > Yes makes sense, maybe you can add some comments into the code too since > > this was overlooked before, > > > > Reviewed-by: Peter Xu > > > > Have you tried to measure how many overheads will this introduce to loading > > each snapshot? > > It's a large overhead actually, between 10-20 milliseconds. This can be mentioned in the commit message. IIUC reset() may or may not be required while loading a snapshot. Normally, a device reset() should reset all dev registers and internal states, OTOH loadvm() will reload most of them once more.. so less efficient. Maybe there's chance to "fix" q35 instead reducing this overhead, but I'll leave that to be your call; to me this fix is clean from maint POV. Thanks, -- Peter Xu