c:\test>perl -MDevel::Size71=total_size 
-E"$a[$_]=1 for 1..1e6; say total_size( \@a )"
32388768

c:\test>perl -MDevel::Size=total_size 
-E"$a[$_]=1 for 1..1e6; say total_size( \@a )"
32388768

c:\test>perl -MDevel::Size71=total_size 
-E"$a[$_]=[1,1] for 1..5e5; say total_size( \@a )"
104194464

c:\test>perl -MDevel::Size=total_size 
-E"$a[$_]=[1,1] for 1..5e5; say total_size( \@a )"
104194464