$ systemctl status chronyd
● chronyd.service - NTP client/server
   Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2019-10-23 13:38:15 CEST; 1 months 4 days ago
     Docs: man:chronyd(8)
           man:chrony.conf(5)
 Main PID: 8102 (chronyd)
   CGroup: /system.slice/chronyd.service
           └─8102 /usr/sbin/chronyd

Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.

$ systemctl status ntpd
Unit ntpd.service could not be found.

##</code><code>##

use strict;
use warnings;
use Time::HiRes qw/time sleep/;

sub negative_timer {
    my $max = $_[0];
    my @time_test;
    my $start = time();
    for (my $i = 0; $i < $max; $i++) {
        $start += 1;
        sleep $start - time();
        $time_test[$i] = time();
    }
    return @time_test;
}