sub sleep_until_low_load {
    my $limit = shift;

    REDO:
    open PROC, "/proc/loadavg" or die $!;
    my $line = <PROC>;
    my $load = $1 if $line =~ m/^\s*([\d\.]+)\s+/;
    close PROC;

    if( $load > $limit ) {
        print "\tsleeping for 5 seconds since $load > $limit\n";
        sleep 5;
        goto REDO;
    }
}