PerlIO::mmap(3perl) Perl Programmers Reference Guide PerlIO::mmap(3perl)

PerlIO::mmap - Memory mapped IO

open my $fh, '<:mmap', $filename;

This layer does "read" and "write" operations by mmap()ing the file if possible, but falls back to the default behavior if not.

"PerlIO::mmap" only exists to use XSLoader to load C code that provides support for using memory mapped IO. One does not need to explicitly "use PerlIO::mmap;".
2021-05-23 perl v5.34.0