On Thu, Jul 9, 2020 at 4:41 PM Alex Bennée <alex.ben...@linaro.org> wrote: > > > Ahmed Karaman <ahmedkhaledkara...@gmail.com> writes: > > > Hi, > > > > The third report of the TCG Continuous Benchmarking series utilizes > > the tools presented in the previous report for comparing the > > performance of 17 different targets across two versions of QEMU. The > > two versions addressed are 5.0 and 5.1-pre-soft-freeze (current state > > of QEMU). > > > > After summarizing the results, the report utilizes the KCachegrind > > tool and dives into the analysis of why all three PowerPC targets > > (ppc, ppc64, ppc64le) had a performance degradation between the two > > QEMU versions. > > It's an interesting degradation especially as you would think that a > change in the softfloat implementation should hit everyone in the same > way. >
That's the same that I've thought of, but while working on next week's report, it appears that this specific change introduced a performance improvement in other targets! > We actually have a tool for benchmarking the softfloat implementation > itself called fp-bench. You can find it in tests/fp. I would be curious > to see if you saw a drop in performance in the following: > > ./fp-bench -p double -o cmp > I ran the command before and after the commit introducing the degradation. Both runs gave results varying between 600~605 MFlops. Running with Callgrind and the Coulomb benchmark, the results were: Number of instructions before: 12,715,390,413 Number of isntructions after: 13,031,104,137 > > > > Report link: > > https://ahmedkrmn.github.io/TCG-Continuous-Benchmarking/QEMU-5.0-and-5.1-pre-soft-freeze-Dissect-Comparison/ > > If you identify a drop in performance due to a commit linking to it from > the report wouldn't be a bad idea so those that want to quickly > replicate the test can do before/after runs. > Report number 5 will introduce a new tool for detecting commits causing performance improvements and degradations. The report will utilize this tool to find out the specific commit introducing these changes. > > > > 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 > > > > Best regards, > > Ahmed Karaman > > > -- > Alex Bennée Best regards, Ahmed Karaman