Linux's Early Boot-Time Physical Memory Allocator Sees Big Speed-Up: ~268s To ~50ms

Linux 7.4's memblock pull request includes a performance fix to the early boot physical memory allocator in mm/memblock.c. Google engineer Tarun Sahu found that region lookups in memblock_add_range() and memblock_isolate_range() used a linear search, which becomes very slow under heavy fragmentation, such as with Kernel Handover (KHO).