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That's all we know. 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 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: =?utf-8?B?THVrw6HFoQ==?= Doktor , QEMU Developers , Aleksandar Markovic , luoyonggang@gmail.com, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Ahmed Karaman writes: > Hi, > > The fifth report of the TCG Continuous Benchmarking project concludes > a mini-series of three reports that dealt with the performance > comparison and analysis of QEMU 5.0 and 5.1-pre-soft-freeze. > > The report presents a new Python script that utilizes "git bisect" for > running a binary search within a specified range of commits to > automatically detect the commit causing a performance improvement or > degradation. Excellent stuff. > The new script is then used to find the commit introducing the PowerPC > performance degradation as well as that introducing the performance > improvement in MIPS. The results obtained for both commits proves the > correctness of the conclusions and analyses presented in the two > previous reports. I can certainly envision a mechanism where 0673ec slows things down. I wonder if it would come back if instead of inline function calls we ended up making concrete flattend versions, e.g.: bool QEMU_FLATTEN float64_eq(float64 a, float64 b, float_status *s) { return float64_compare(a, b, s) =3D=3D float_relation_equal; } PPC is of course more affected by these changes than others because HARDFLOAT never gets a chance to kick in. Looking at the objdump of f64_compare there should surely be an opportunity to loose some of the branches when looking for a certain test result? > > Report link: > https://ahmedkrmn.github.io/TCG-Continuous-Benchmarking/Finding-Commits-A= ffecting-QEMU-Performance/ > > Previous reports: > Report 1 - Measuring Basic Performance Metrics of QEMU: > https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg06692.html > Report 2 - Dissecting QEMU Into Three Main Parts: > https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg09441.html > Report 3 - QEMU 5.0 and 5.1-pre-soft-freeze Dissect Comparison: > https://lists.gnu.org/archive/html/qemu-devel/2020-07/msg01978.html > Report 4 - Listing QEMU Helpers and Function Callees: > https://lists.gnu.org/archive/html/qemu-devel/2020-07/msg04227.html > > Best regards, > Ahmed Karaman --=20 Alex Benn=C3=A9e