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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id ph4-20020a0562144a4400b0066da90f0c19sm3515940qvb.24.2023.10.30.09.09.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Oct 2023 09:09:52 -0700 (PDT) Date: Mon, 30 Oct 2023 12:09:13 -0400 From: Peter Xu To: Joao Martins Cc: qemu-devel@nongnu.org, Fabiano Rosas , Juan Quintela Subject: Re: [PATCH 0/3] migration: Downtime tracepoints Message-ID: References: <20231026155337.596281-1-peterx@redhat.com> <778f6c92-221c-41d2-b0ae-4f5f4a208f65@oracle.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: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.483, 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 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, Oct 30, 2023 at 11:13:55AM -0400, Peter Xu wrote: > > Perhaps it is easy to wrap the checkpoint tracepoint in its own function to > > allow extension of something else e.g. add the timestamp (or any other data into > > the checkpoints) or do something in a particular checkpoint of the migration. > > The timing function from qemu would give qemu own idea of time (directly > > correlable with the downtime metric that applications consume) which would be > > more consistent? though I am at too minds on this whether to rely on tracing > > stamps or align with what's provided to applications. > > Yes it should be more consistent. Let me add them into the checkpoints. I just noticed dst qemu doesn't have downtime_start to offset.. Only offset the src downtime checkpoints will make it less consistent. I'll leave this one for later. Posting a new version soon. -- Peter Xu