Suppress warning from output

-v will print Ruby version and also set $VERBOSE to true.

-W0 sets $VERBOSE to nil

Rakefile

@@ -2,12 +2,12 @@ desc "run benchmark in current ruby"
 task :run_benchmark do
   Dir["code/general/*.rb"].each do |benchmark|
     puts "$ ruby -v #{benchmark}"
-    system("ruby", "-v", benchmark)
+    system("ruby", "-v", "-W0", benchmark)
   end
 
   Dir["code/*/*.rb"].reject { |path| path =~ /^code\/general/ }.each do |benchmark|
     puts "$ ruby -v #{benchmark}"
-    system("ruby", "-v", benchmark)
+    system("ruby", "-v", "-W0", benchmark)
   end
 end