def determine_private_dirty_rss(pid)
  		total = 0
  		File.read("/proc/#{pid}/smaps").split("\n").each do |line|
  			line =~ /^(Private)_Dirty: +(\d+)/
  			if $2
  				total += $2.to_i
  			end
  		end
  		if total == 0
  			return nil
  		else
  			return total
  		end
  	rescue Errno::EACCES, Errno::ENOENT
  		return nil
  	end
def determine_private_dirty_rss(pid)
  		total = 0
  		File.read("/proc/#{pid}/smaps").split("\n").each do |line|
  			line =~ /^(Private)_Dirty: +(\d+)/
  			if $2
  				total += $2.to_i
  			end
  		end
  		if total == 0
  			return nil
  		else
  			return total
  		end
  	rescue Errno::EACCES, Errno::ENOENT
  		return nil
  	end
Returns the private dirty RSS for the given process, in KB.