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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id c8-20020a05622a058800b003f6ac526568sm1354689qtb.39.2023.10.04.10.19.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Oct 2023 10:19:21 -0700 (PDT) Date: Wed, 4 Oct 2023 13:19:20 -0400 From: Peter Xu To: Joao Martins Cc: qemu-devel@nongnu.org, Juan Quintela , Leonardo Bras , Eric Blake , Markus Armbruster , Avihai Horon , Yishai Hadas , "Maciej S. Szmigiero" Subject: Re: [PATCH 0/5] migration: Downtime observability improvements Message-ID: References: <20230926161841.98464-1-joao.m.martins@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230926161841.98464-1-joao.m.martins@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: -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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, T_SPF_HELO_TEMPERROR=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, Sep 26, 2023 at 05:18:36PM +0100, Joao Martins wrote: > For now, mainly precopy data, and here I added both tracepoints and > QMP stats via query-migrate. Postcopy is still missing. IIUC many of those will cover postcopy too, but not all? I think the problem is postcopy didn't update downtime_start, however it updates MigrationState.downtime, and probably we can start to keep it more like precopy, e.g., in postcopy_start(), where downtime_start can be time_at_stop (or it can be more accurate; now it's probably fetching the timestamp too early). Basically if we want to expose anything, especially some qapi object, IMHO we'd better make it work for both pre/post copy because otherwise it'll be hard for mgmt app to know which qemu supports precopy only, and which support both (if we'll add that for postcopy too). Thanks, -- Peter Xu