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([2607:fb90:4561:1dc5:19c7:835d:6676:d30c]) by smtp.gmail.com with ESMTPSA id k9-20020a4a8509000000b0059d58430c2asm136157ooh.20.2024.02.16.14.28.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 16 Feb 2024 14:28:13 -0800 (PST) Message-ID: <6f9b69ba-f694-4c22-b6fc-110a96bb1ba8@linaro.org> Date: Fri, 16 Feb 2024 12:28:09 -1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 00/10] Optimize buffer_is_zero Content-Language: en-US To: Alexander Monakov Cc: qemu-devel@nongnu.org, mmromanov@ispras.ru References: <20240215081449.848220-1-richard.henderson@linaro.org> <72d0e01e-ca54-4fc1-805c-b8de7175d64f@linaro.org> <2d211317-873e-43c6-a246-bd8bf84f048b@linaro.org> <08ce9292-75a0-4092-a12e-9a12826847b0@linaro.org> From: Richard Henderson In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::c2f; envelope-from=richard.henderson@linaro.org; helo=mail-oo1-xc2f.google.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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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 2/16/24 10:20, Alexander Monakov wrote: > FWIW, in situations like these I always recommend to run perf with fixed > sampling rate, i.e. 'perf record -e cycles:P -c 100000' or 'perf record -e > cycles/period=100000/P' to make sample counts between runs of different > duration directly comparable (displayed with 'perf report -n'). I've re-done the numbers with fixed period, as suggested, and the difference between v3 and v4+ is in the sampling noise, differing about 0.3%. r~