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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id x13sm11330967wro.31.2021.05.18.05.48.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 May 2021 05:48:39 -0700 (PDT) Subject: Re: [PATCH 2/3] ci: do not use #processors+1 jobs, #processors is enough To: =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= References: <20210518084139.97957-1-pbonzini@redhat.com> <20210518084139.97957-3-pbonzini@redhat.com> <40f9d46b-d234-c029-3ba2-f5dcac8b87fc@redhat.com> <7155c55a-1566-d7f0-d59e-ee48707302cf@redhat.com> From: Paolo Bonzini Message-ID: <885e30da-8d6d-7d58-7733-f66477633e65@redhat.com> Date: Tue, 18 May 2021 14:48:39 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.374, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , alex.bennee@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 18/05/21 14:43, Daniel P. Berrangé wrote: > I'd be surprised if you can measure any statistically reliable difference > at all wrt public CI. I've tried measuring CI performance for small changes > and found it impossible in short time frames, as the deviation between runs > is way too large. GitLab CI speeds tend to slow down as the day goes on and > US wakes up, so by time you run QEMU CI a second time in the day, it will > be slower. They clearly overcommit resources on the cloud host so you're > at the mercy of whatever else is running. Yeah, I was going to test it locally (using CPU offlining and hugetlbfs to simulate a 4-CPU machine with not that much memory). Paolo