diff --git a/ChangeLog b/ChangeLog
index 97fee0214d..32c61ca6e4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Oct 17 08:46:47 2012  Koichi Sasada  <ko1@atdot.net>
+
+	* benchmark/bm_vm2_dstr.rb: add a benchmark to measure
+	  performance of dynamic generated string ("foo#{bar}baz").
+
 Wed Oct 17 08:32:46 2012  Koichi Sasada  <ko1@atdot.net>
 
 	* compile.c (compile_dstr_fragments): use `putobject' instead of
diff --git a/benchmark/bm_vm2_dstr.rb b/benchmark/bm_vm2_dstr.rb
new file mode 100644
index 0000000000..58c0f7bbc3
--- /dev/null
+++ b/benchmark/bm_vm2_dstr.rb
@@ -0,0 +1,6 @@
+i = 0
+x = y = 'z'
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end