diff --git a/[refs] b/[refs]
index 21f8ba3b925a..82a5fc5b5756 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 41c21a68308f2f268a01ec1a7fa5f650e320a0f3
+refs/heads/master: 67cbbd7f1838cc8f6900f39d860d6c2e1f86cf61
diff --git a/trunk/tools/perf/Makefile b/trunk/tools/perf/Makefile
index e011b5060f92..fa043404479e 100644
--- a/trunk/tools/perf/Makefile
+++ b/trunk/tools/perf/Makefile
@@ -15,6 +15,16 @@ endif
 
 # Define V to have a more verbose compile.
 #
+# Define O to save output files in a separate directory.
+#
+# Define ARCH as name of target architecture if you want cross-builds.
+#
+# Define CROSS_COMPILE as prefix name of compiler if you want cross-builds.
+#
+# Define NO_LIBPERL to disable perl script extension.
+#
+# Define NO_LIBPYTHON to disable python script extension.
+#
 # Define PYTHON to point to the python binary if the default
 # `python' is not correct; for example: PYTHON=python2
 #
@@ -32,6 +42,10 @@ endif
 # Define NO_DWARF if you do not want debug-info analysis feature at all.
 #
 # Define WERROR=0 to disable treating any warnings as errors.
+#
+# Define NO_NEWT if you do not want TUI support.
+#
+# Define NO_DEMANGLE if you do not want C++ symbol demangling.
 
 $(OUTPUT)PERF-VERSION-FILE: .FORCE-PERF-VERSION-FILE
 	@$(SHELL_PATH) util/PERF-VERSION-GEN $(OUTPUT)