add tool for performance impact mesurement

perf.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -eu
+
+num=1000000
+
+rm -f perf_*.log
+
+for i in `jot 10`; do
+	/usr/bin/time st -e                      jot $num 2>>perf_0.log
+done
+
+for i in `jot 10`; do
+	/usr/bin/time st -e ./ptty               jot $num 2>>perf_1.log
+done
+
+for i in `jot 10`; do
+	/usr/bin/time st -e ./ptty ./ptty        jot $num 2>>perf_2.log
+done
+
+for i in `jot 10`; do
+	/usr/bin/time st -e ./ptty ./ptty ./ptty jot $num 2>>perf_3.log
+done