8315781: Reduce the max value of GCDrainStackTargetSize

Reviewed-by: tschatzl, iwalulya

Author: albertnetymk

src/hotspot/share/gc/g1/g1Arguments.cpp

@@ -230,11 +230,6 @@ void G1Arguments::initialize() {
     FLAG_SET_DEFAULT(ParallelRefProcEnabled, true);
   }
 
-  // By default do not let the target stack size to be more than 1/4 of the entries
-  if (FLAG_IS_DEFAULT(GCDrainStackTargetSize)) {
-    FLAG_SET_ERGO(GCDrainStackTargetSize, MIN2(GCDrainStackTargetSize, TASKQUEUE_SIZE / 4));
-  }
-
 #ifdef COMPILER2
   // Enable loop strip mining to offer better pause time guarantees
   if (FLAG_IS_DEFAULT(UseCountedLoopSafepoints)) {

src/hotspot/share/gc/g1/g1ConcurrentMark.cpp

@@ -2318,7 +2318,7 @@ void G1CMTask::drain_local_queue(bool partially) {
   // of things to do) or totally (at the very end).
   uint target_size;
   if (partially) {
-    target_size = MIN2(_task_queue->max_elems() / 3, GCDrainStackTargetSize);
+    target_size = GCDrainStackTargetSize;
   } else {
     target_size = 0;
   }

src/hotspot/share/gc/parallel/psPromotionManager.cpp

@@ -183,8 +183,7 @@ PSPromotionManager::PSPromotionManager() {
   if (ParallelGCThreads == 1) {
     _target_stack_size = 0;
   } else {
-    // don't let the target stack size to be more than 1/4 of the entries
-    _target_stack_size = MIN2(GCDrainStackTargetSize, (queue_size / 4));
+    _target_stack_size = GCDrainStackTargetSize;
   }
 
   _array_chunk_size = ParGCArrayScanChunk;

src/hotspot/share/gc/shared/gc_globals.hpp

@@ -687,7 +687,7 @@
   product(uint, GCDrainStackTargetSize, 64,                                 \
           "Number of entries we will try to leave on the stack "            \
           "during parallel gc")                                             \
-          range(0, (UINT_MAX - 1) / 2)                                      \
+          range(0, 8 * 1024)                                                \
                                                                             \
   product(uint, GCCardSizeInBytes, 512,                                     \
           "Card table entry size (in bytes) for card based collectors")     \