Constant libmimalloc_sys::mi_option_reserve_huge_os_pages

pub const mi_option_reserve_huge_os_pages: mi_option_t = 7;

Option (experimental) The number of huge OS pages (1GiB in size) to reserve at the start of the program.

This reserves the huge pages at startup and sometimes this can give a large (latency) performance improvement on big workloads. Usually it is better to not use MIMALLOC_LARGE_OS_PAGES in combination with this setting. Just like large OS pages, use with care as reserving contiguous physical memory can take a long time when memory is fragmented (but reserving the huge pages is done at startup only once). Note that we usually need to explicitly enable huge OS pages (as on Windows and Linux)). With huge OS pages, it may be beneficial to set the setting mi_option_eager_commit_delay=N (N is 1 by default) to delay the initial N segments (of 4MiB) of a thread to not allocate in the huge OS pages; this prevents threads that are short lived and allocate just a little to take up space in the huge OS page area (which cannot be reset).