if($chunk_size=~/(\d+)([mMgG])/) {
    my $numb=$1;
    my $tp=$2;
    SW: {
        ($tp eq "g" || $tp eq "G") && do {
            $numb*=1024*1024*1024;
            $size=$numb;
            last SW;
        };
        ($tp eq "m" || $tp eq "M") && do {
            $numb*=1024*1024;
            $size=$numb;
            last SW;
        };
    }
}
else {
    $size=$chunk_size;
}