6864886: G1: rename -XX parameters related to update buffers

Summary: renaming a couple of update buffer-related parameters to make them more understandable and consistent.
Reviewed-by: iveresov, ysr

src/share/vm/gc_implementation/g1/concurrentG1RefineThread.cpp

@@ -104,17 +104,17 @@ void ConcurrentG1RefineThread::run() {
     double start_vtime_sec; // only used when G1SmoothConcRefine is on
     int prev_buffer_num; // only used when G1SmoothConcRefine is on
     // This thread activation threshold
-    int threshold = DCQBarrierProcessCompletedThreshold * _worker_id;
+    int threshold = G1UpdateBufferQueueProcessingThreshold * _worker_id;
     // Next thread activation threshold
-    int next_threshold = threshold + DCQBarrierProcessCompletedThreshold;
-    int deactivation_threshold = MAX2<int>(threshold - DCQBarrierProcessCompletedThreshold / 2, 0);
+    int next_threshold = threshold + G1UpdateBufferQueueProcessingThreshold;
+    int deactivation_threshold = MAX2<int>(threshold - G1UpdateBufferQueueProcessingThreshold / 2, 0);
 
     if (G1SmoothConcRefine) {
       lower_limit = 0;
       start_vtime_sec = os::elapsedVTime();
       prev_buffer_num = (int) dcqs.completed_buffers_num();
     } else {
-      lower_limit = DCQBarrierProcessCompletedThreshold / 4; // For now.
+      lower_limit = G1UpdateBufferQueueProcessingThreshold / 4; // For now.
     }
     while (dcqs.apply_closure_to_completed_buffer(_worker_id + _worker_id_offset, lower_limit)) {
       double end_vtime_sec;

src/share/vm/gc_implementation/g1/dirtyCardQueue.cpp

@@ -80,8 +80,8 @@ void DirtyCardQueueSet::initialize(Monitor* cbl_mon, Mutex* fl_lock,
                                    int max_completed_queue,
                                    Mutex* lock, PtrQueueSet* fl_owner) {
   PtrQueueSet::initialize(cbl_mon, fl_lock, max_completed_queue, fl_owner);
-  set_buffer_size(DCQBarrierQueueBufferSize);
-  set_process_completed_threshold(DCQBarrierProcessCompletedThreshold);
+  set_buffer_size(G1UpdateBufferSize);
+  set_process_completed_threshold(G1UpdateBufferQueueProcessingThreshold);
 
   _shared_dirty_card_queue.set_lock(lock);
   _free_ids = new FreeIdSet((int) num_par_ids(), _cbl_mon);

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -1591,7 +1591,7 @@ jint G1CollectedHeap::initialize() {
 
   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
                                                 DirtyCardQ_FL_lock,
-                                                G1DirtyCardQueueMax,
+                                                G1UpdateBufferQueueMaxLength,
                                                 Shared_DirtyCardQ_lock);
 
   if (G1DeferredRSUpdate) {

src/share/vm/gc_implementation/g1/g1_globals.hpp

@@ -167,9 +167,16 @@
   develop(bool, G1DisablePostBarrier, false,                                \
           "Disable generation of post-barrier (i.e., RS barrier)   ")       \
                                                                             \
-  product(intx, G1DirtyCardQueueMax, 30,                                    \
-          "Maximum number of completed RS buffers before mutator threads "  \
-          "start processing them.")                                         \
+  product(intx, G1UpdateBufferSize, 256,                                    \
+          "Size of an update buffer")                                       \
+                                                                            \
+  product(intx, G1UpdateBufferQueueProcessingThreshold, 5,                  \
+          "Number of enqueued update buffers that will "                    \
+          "trigger concurrent processing")                                  \
+                                                                            \
+  product(intx, G1UpdateBufferQueueMaxLength, 30,                           \
+          "Maximum number of enqueued update buffers before mutator "       \
+          "threads start processing new ones instead of enqueueing them")   \
                                                                             \
   develop(intx, G1ConcRSLogCacheSize, 10,                                   \
           "Log base 2 of the length of conc RS hot-card cache.")            \

src/share/vm/runtime/globals.hpp

@@ -2924,12 +2924,6 @@ class CommandLineFlags {
           "how many entries we'll try to leave on the stack during "        \
           "parallel GC")                                                    \
                                                                             \
-  product(intx, DCQBarrierQueueBufferSize, 256,                             \
-          "Number of elements in a dirty card queue buffer")                \
-                                                                            \
-  product(intx, DCQBarrierProcessCompletedThreshold, 5,                     \
-          "Number of completed dirty card buffers to trigger processing.")  \
-                                                                            \
   /* stack parameters */                                                    \
   product_pd(intx, StackYellowPages,                                        \
           "Number of yellow zone (recoverable overflows) pages")            \