b2378168a4
Add the 'M' and 'm' MALLOC_OPTIONS flags, which control the maximum medium size class. Relax the cap on small/medium run size to arena_maxclass. Reduce arena_run_reg_dalloc() integer division code complexity. Increase the default chunk size from 1MiB to 4MiB.
jemalloc is a general-purpose scalable concurrent malloc(3) implementation. The INSTALL file contains information on how to configure, build, and install jemalloc.