int fd = open(filename, O_RDONLY);
void* buffer = mmap(NULL, size_bytes, PROT_READ, (MAP_HUGETLB | MAP_HUGE_1GB), fd, 0);
This doesn't work with a file on my ext4 volume. What am I missing?
This doesn't work with a file on my ext4 volume. What am I missing?
See a quick example I whipped up here: https://github.com/inetknght/mmap-hugetlb
> Huge page (Huge TLB) mappings
> For mappings that employ huge pages, the requirements for the arguments of mmap() and munmap() differ somewhat from the requirements for mappings that use the native system page size.
> For mmap(), offset must be a multiple of the underlying huge page size. The system automatically aligns length to be a multiple of the underlying huge page size.
Ensure that the file is at least the page size, and preferably sized to align with a page boundary. Then also ensure that the length parameter (size_bytes in your example) is also aligned to a boundary.
There are also other important things to understand for these flags, which are described in the documentation, such as information available from /sys/kernel/mm/hugepages