Hello Alex, I’m investigating Python 3 performance issues on a Raspberry Pi Yocto build; I appreciate any insights you can provide into the problem.
In my investigation, I noticed that PGO was disabled in all cases due to a small bug. I fixed it in a patch submitted to OE-Core (#139459<https://lists.openembedded.org/g/openembedded-core/message/139459>). Even when PGO is indeed enabled, Python 3 runs significantly slower on Yocto-compiled Python 3.8.3 than the same version compiled on Raspbian. In your patch, 0001-Makefile.pre-use-qemu-wrapper-when-gathering-profile.patch<http://cgit.openembedded.org/openembedded-core/tree/meta/recipes-devtools/python/python3/0001-Makefile.pre-use-qemu-wrapper-when-gathering-profile.patch>, I see that you override the default PROFILE_TASK, which did not explicitly specify test suites, to a command that explicitly provides test suites. How did you decide on these tests? The standard PGO command runs 43 tests, while you specify 7. When I compile Python 3.8.3 on Raspbian, I see no intersection between the 43 tests run by default and the 7 you specify. Additionally, the default module for PROFILE is test while you use test.regrtest. For reference, here’s the results of a simple CPU-bound test. These tests were run on the same Raspberry Pi 4 with same SD card. python3 -m timeit -r 10 --setup ' def fib(n): if n < 2: return n if n == 2: return 1 return fib(n - 1) + fib(n - 2) ' '[fib(n) for n in range(20)]' # Yocto Python 3.8.3 # 10 loops, best of 10: 28.9 msec per loop # 10 loops, best of 10: 29.3 msec per loop # 10 loops, best of 10: 27.9 msec per loop # 10 loops, best of 10: 30.4 msec per loop # Average result: 31.625 msec per loop # Raspbian Python 3.8.3 # 50 loops, best of 10: 7.73 msec per loop # 50 loops, best of 10: 7.72 msec per loop # 50 loops, best of 10: 7.67 msec per loop # 50 loops, best of 10: 7.74 msec per loop # Average result: 7.715 msec per loop # Raspbian speedup: 4.09x Best, Ryan Rowe
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