SmpAllocator becomes less efficient when more than 128 CPUs are trying to use the allocator.

[programmerjake]

Zig Version

commit dc090e9

Steps to Reproduce and Observed Behavior

zig/lib/std/heap/SmpAllocator.zig

Line 49 in dc090e9

const max_thread_count = 128;

if you use a computer with more than 128 CPUs (e.g. a dual-socket AMD Epyc 9965 has 768 CPUs (counting each thread as a CPU)), then the allocator will make all additional threads busy-wait when more than 128 threads are in the allocator at any time.

Expected Behavior

dynamically adjust to higher CPU counts instead of using a static array.