Provided by: perl-doc_5.22.1-9ubuntu0.9_all 

NAME
PerlIO::mmap - Memory mapped IO
SYNOPSIS
open my $fh, '<:mmap', $filename;
DESCRIPTION
This layer does "read" and "write" operations by mmap()ing the file if possible, but falls back to the
default behavior if not.
IMPLEMENTATION NOTE
"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;".
perl v5.22.1 2020-10-19 PerlIO::mmap(3perl)