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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id 27-20020a05620a079b00b00767da9b6ae9sm4283810qka.11.2023.08.01.10.09.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Aug 2023 10:09:24 -0700 (PDT) Date: Tue, 1 Aug 2023 13:09:22 -0400 From: Peter Xu To: Andrei Gudkov Cc: qemu-devel@nongnu.org, quintela@redhat.com, leobras@redhat.com, eblake@redhat.com, armbru@redhat.com Subject: Re: [PATCH] migration/calc-dirty-rate: millisecond precision period Message-ID: References: <8571da37847f9bb39b84e62ef4998e68ef3c10d1.1688028297.git.gudkov.andrei@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8571da37847f9bb39b84e62ef4998e68ef3c10d1.1688028297.git.gudkov.andrei@huawei.com> 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: -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_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-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 Thu, Jun 29, 2023 at 11:59:03AM +0300, Andrei Gudkov wrote: > Introduces alternative argument calc-time-ms, which is the > the same as calc-time but accepts millisecond value. > Millisecond precision allows to make predictions whether > migration will succeed or not. To do this, calculate dirty > rate with calc-time-ms set to max allowed downtime, convert > measured rate into volume of dirtied memory, and divide by > network throughput. If the value is lower than max allowed > downtime, then migration will converge. > > Measurement results for single thread randomly writing to > a 24GiB region: > +--------------+--------------------+ > | calc-time-ms | dirty-rate (MiB/s) | > +--------------+--------------------+ > | 100 | 1880 | > | 200 | 1340 | > | 300 | 1120 | > | 400 | 1030 | > | 500 | 868 | > | 750 | 720 | > | 1000 | 636 | > | 1500 | 498 | > | 2000 | 423 | > +--------------+--------------------+ > > Signed-off-by: Andrei Gudkov Andrei, do you plan to enhance the commit message and data in a repost? I assume you may want to have your data points updated after the discussion, and it won't need to be in a rush as it will only land 8.2. The patch itself looks fine to me: Acked-by: Peter Xu Thanks, -- Peter Xu