#!/usr/local/bin/perl
#
# requires textproc/p5-XML-LibXML
#
use warnings;
use strict;

use feature 'say';
use XML::LibXML;

my ($offset) = @ARGV;

if (not defined $offset) {
	$offset = 10;
}

my $filename = 'vmstat.xml';


my %dict;



while (1) {
	say scalar localtime();
	say "------------------------";
	system("/usr/bin/vmstat -z --libxo xml >$filename"); 
	my $doc = XML::LibXML->load_xml(location => $filename); 
	my $c = 0;
	foreach my $id ($doc->findnodes('//zone')) {
		my $name=$id->findvalue('name');
		my $used=$id->findvalue('used');

		my $val = int($used);

		if ($name eq "vm pgcache") {
			$name = $name . "_$c";
			$c++;
		}
		
		if (exists $dict{$name}) {
			my $v0=$dict{$name} + $offset;

			if ($v0 <= $val) {
format DIFF_V0V1 =
	@<<<<<<<<<<<<<<<<<<<<<< @######## => @########
	$name,$dict{$name},$val
.
				$~ = "DIFF_V0V1";
				write;
				$dict{$name} = $val;
			}
		} else {
			$dict{$name} = $val;
		}
	}

	say '';

	sleep(5);
}