report_mem( 'program start' ); my $big = 'x' x 100_000_000; report_mem( 'after making big string' ); take_big_arg( $big ); sub take_big_arg { printf "got %d characters\n", length $_[0]; report_mem( 'passed to function' ); } sub report_mem { my ( $msg ) = @_; printf "%d %s\n", my_mem(), $msg; } sub my_mem { my ($proc_info) = grep { $_->[2] == $$ } map { [ split ] } `ps l | tail -n +2`; return $proc_info->[6]; } __END__ 13124 program start 208444 after making big string got 100000000 characters 208444 passed to function