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

use XML::LibXML;

my $filename = 'vmstatm.xml';
my %dict;

my ($offset) = @ARGV;

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

while (1) {
	say scalar localtime();
	say "------------------------";
	system("/usr/bin/vmstat -m --libxo xml >$filename"); 
	my $doc = XML::LibXML->load_xml(location => $filename); 
	foreach my $id ( $doc->findnodes('//memory')) {
		my $name=$id->findvalue('type');
		my $used=$id->findvalue('memory-use');
		if (exists $dict{$name}) {
			my $v0=$dict{$name} + $offset;

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

	say '';
	sleep(5);
}