A similar problem was discussed in The most precise second (timer).

If you don't need to be almost precise, something like this might be good enough:

#! /usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use Time::HiRes qw{ time sleep };

sub func { sleep rand 0.05 }

my $t0 = 0;
while (1) {
    if (time - $t0 >= 0.1) {
        say $t0 = time;
        func();
    }
}
[download]

On my machine, it shows:

1597188470.0211
1597188470.1211
1597188470.2211
1597188470.3211
1597188470.4211
1597188470.52111
1597188470.62111
1597188470.72111
1597188470.82111
1597188470.92111
1597188471.02111
1597188471.12111
1597188471.22112
1597188471.32112
1597188471.42112
1597188471.52112
1597188471.62112
1597188471.72112
1597188471.82113
[download]