--- old/test/Makefile	2011-09-21 18:02:10.500451875 +0800
+++ new/test/Makefile	2011-09-21 18:02:09.950451875 +0800
@@ -357,15 +357,19 @@
 ifndef USE_JTREG_SAMEVM
   USE_JTREG_SAMEVM=false
 endif
-# With samevm, you cannot use -javaoptions?
+# With samevm, you cannot use -javaoptions? (-agentvm is more reliable -samevm)
 ifeq ($(USE_JTREG_SAMEVM),true)
-  JTREG_SAMEVM_OPTION = -samevm
+  JTREG_SAMEVM_OPTION = -agentvm
   EXTRA_JTREG_OPTIONS += $(JTREG_SAMEVM_OPTION) $(JAVA_ARGS) $(JAVA_ARGS:%=-vmoption:%)
   JTREG_TEST_OPTIONS = $(JAVA_VM_ARGS:%=-vmoption:%)
 else
   JTREG_TEST_OPTIONS = $(JAVA_ARGS:%=-javaoptions:%) $(JAVA_VM_ARGS:%=-vmoption:%)
 endif
 
+ifdef CONCURRENCY
+  EXTRA_JTREG_OPTIONS += -concurrency:$(CONCURRENCY)
+endif
+
 # Some tests annoy me and fail frequently
 PROBLEM_LIST=ProblemList.txt
 PROBLEM_LISTS=$(PROBLEM_LIST) $(wildcard closed/$(PROBLEM_LIST))