[eval.py] add host command line option

eval.py

@@ -619,6 +619,8 @@ if __name__ == '__main__':
                         '--local',
                         help='run benchmark on localhost',
                         action='store_true')
+    parser.add_argument('--host',
+                        help='host running the echo servers')
     parser.add_argument('-r',
                         '--runs',
                         help='benchmark runs',
@@ -713,6 +715,13 @@ if __name__ == '__main__':
 
         HOST = "localhost"
 
+    if args.host:
+        if HOST == 'localhost':
+            print('ERROR: host optioan and local option can not be passed at once')
+            sys.exit(1)
+
+        HOST = args.host
+
     if args.implementations:
         SERVER_CMDS = {
             i: c