[jasone]

jemalloc does not assume a particular page size; it configures page size at build time. By default the configured page size is the actual page size (usually 4KiB), but optionally it's some power-of-two multiple of the actual page size. In the early days of jemalloc the page size was queried at startup rather than burned into the binary, but that dynamic flexibility was never of any use in practice, and it inhibited compiler optimizations.