#!/usr/bin/perl -w
use strict;
use XML::Simple;

my $parser = new XML::Simple(ForceArray => ['process']);
my $ref = $parser->XMLin('c:\temp\file.xml');
foreach my $host (keys(%$ref)){
  foreach my $proc (keys(%{$ref->{$host}->{process}})){
    print "$proc is running on $host\n";
  }
}