Optimise pretty_size function using log()

webif/lib/pretty_size

@@ -3,9 +3,19 @@ if {![exists -proc pretty_size]} {
 	proc pretty_size {size} {
 		set units {bytes KiB MiB GiB TiB}
 
-		for {set i 0; set l [llength $units]; incr l -1} {
-		    $size > 1023 && $i < $l} {incr i} {
-			set size $($size / 1024.0)
+#		for {set i 0; set l [llength $units]; incr l -1} {
+#		    $size > 1023 && $i < $l} {incr i} {
+#			set size $($size / 1024.0)
+#		}
+
+		# We need to know how many powers of 1024 there are in
+		# size. This calculates the answer effeciently. Testing
+		# shows that this version takes 2/3 the time of the above.
+		if {$size == 0} {
+			set i 0
+		} else {
+			set i $(int(log($size) / log(1024)))
+			set size $($size / 1024.0 ** $i)
 		}
 
 		set size [string trimright \