Merge pull request #450 from hnyman/stat-memory

statistics: support better autoscaling in rrdtool, improve memory graph's y-axis

applications/luci-app-statistics/luasrc/statistics/rrdtool.lua

@@ -457,6 +457,12 @@ function Graph._generic( self, opts, plugin, plugin_instance, dtype, index )
 			_ti ( _args, "-X" )
 			_ti ( _args, opts.units_exponent )
 		end
+		if opts.alt_autoscale then
+			_ti ( _args, "-A" )
+		end
+		if opts.alt_autoscale_max then
+			_ti ( _args, "-M" )
+		end
 
 		-- store additional rrd options
 		if opts.rrdopts then

applications/luci-app-statistics/luasrc/statistics/rrdtool/definitions/memory.lua

@@ -17,6 +17,8 @@ function rrdargs( graph, plugin, plugin_instance, dtype )
 		title = "%H: Memory usage",
 		vlabel = "MB",
 		number_format = "%5.1lf%s",
+		y_min = "0",
+		alt_autoscale_max = true,
 		data = {
 			instances = { 
 				memory = { "free", "buffered", "cached", "used" }