Almost:

$clocks{$pin_name}{'jit'} = \@jit_values;
[download]

You needed to assign an arrayref as value...

Update upon further inspection...

my @jitter_values = $hashref->{'jit'};
[download]

should be

my @jitter_values = @{ $hashref->{'jit'} };
[download]

What @{ ... } does is dereference the arrayref into an ordinary list.

[ ar0n ]