use Devel::Peek qw( Dump );
$Devel::Peek::pv_limit = 
$Devel::Peek::pv_limit = 10;
my $n;

$_ = "x" x 1e8;
$_ .= "x";  # Force unsharing.
Dump( $_ );
$n = 1249;
$_ = "x" x $n;
Dump( $_ );

$_ = "x" x 1e8;
$_ .= "x";  # Force unsharing.
Dump( $_ );
$n = 1250;
$_ = "x" x $n;
Dump( $_ );

__END__

5.042000
SV = PV(0x21d90461a70) at 0x21d9049cb58
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0x21d9dd19060 "xxxxxxxxxx"...\0
  CUR = 100000001
  LEN = 100000002
SV = PV(0x21d90461a70) at 0x21d9049cb58
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0x21d9dd19060 "xxxxxxxxxx"...\0
  CUR = 1249
  LEN = 100000002
SV = PV(0x21d90461a70) at 0x21d9049cb58
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0x21d9dd1e060 "xxxxxxxxxx"...\0
  CUR = 100000001
  LEN = 100000002
SV = PV(0x21d90461a70) at 0x21d9049cb58
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0x21d90497bd0 "xxxxxxxxxx"...\0
  CUR = 1250
  LEN = 1256