https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127893
--- Comment #7 from [email protected] --- (In reply to Drea Pinski from comment #2) > Note aarch64-darwin support is not upstream yet. So the question is does > this also happen on x86_64-darwin; I would assume yes. > > Also this seems like something also to report to Apple about their rwlock > implmentation to improve there. I have access to a Macmini6,2 with Quad-Core Intel Core i7 (Hyper-Threading Technology: Enabled) running macOS 13.7.8 (IOW very old). Homebrew gcc@13 and gcc@15. For the reproducer, elapsed times are: Threads GCC13.4.0 (s) GCC15.2.0 (s) ------- ----------- ----------- 1 0.7244 0.7529 2 0.9903 0.5647 3 1.1185 0.4970 4 2.3504 3.4938 5 3.0009 28.8442 6 4.6942 35.0416 7 6.0702 45.9977 8 5.8494 58.0890 The GCC13 binary gets gracefully slower with every added thread. The GCC15 binary improves until 3 threads, then collapses. I'll try to find a newer Mac.
