use knobs by default

DefineOptions.cmake

@@ -108,16 +108,16 @@ if(LINUX)
   set(ORDERING_POLICY "lifo")
   set(FITTING_POLICY "good")
   set(GOOD_FIT_PERCENTAGE 0.8)
-  set(WITH_COALESCING "fixed")
+  set(WITH_COALESCING "variable")
   set(MAX_COALESCE_SIZE 60000)
-  set(WITH_SPLITTING "fixed")
+  set(WITH_SPLITTING "variable")
   set(MIN_SPLITTING_SIZE 64)
   set(FREELIST_COALESCE_AFTER_SPLIT ON)
   set(TRACE_LEVEL 3)
   set(WITH_REALLOC ON)
   set(WITH_CALLOC ON)
   set(WITH_MEMALIGN ON)
-  set(WITH_KNOBS OFF)
+  set(WITH_KNOBS ON)
   set(STATS "global")
   set(REQUEST_SIZE_INFO ON)
   set(WITH_SHARED_LIB ON)