src/share/vm/runtime/arguments.cpp

rev 3708 : 8000244: G1: Ergonomically set MarkStackSize and use virtual space for global marking stack
Summary: Set the value of MarkStackSize to a value based on the number of parallel marking threads with a reasonable minimum. Expand the marking stack if we have to restart marking due to an overflow up to a reasonable maximum. Allocate the underlying space for the marking stack from virtual memory.
Reviewed-by: jmasa

*** 1500,1516 ****
    if (ParallelGCThreads == 0) {
      FLAG_SET_DEFAULT(ParallelGCThreads,
                       Abstract_VM_Version::parallel_worker_threads());
    }
  
!   if (FLAG_IS_DEFAULT(MarkStackSize)) {
!     FLAG_SET_DEFAULT(MarkStackSize, 128 * TASKQUEUE_SIZE);
!   }
!   if (PrintGCDetails && Verbose) {
!     tty->print_cr("MarkStackSize: %uk  MarkStackSizeMax: %uk",
!       MarkStackSize / K, MarkStackSizeMax / K);
!     tty->print_cr("ConcGCThreads: %u", ConcGCThreads);
    }
  
    if (FLAG_IS_DEFAULT(GCTimeRatio) || GCTimeRatio == 0) {
      // In G1, we want the default GC overhead goal to be higher than
      // say in PS. So we set it here to 10%. Otherwise the heap might
--- 1500,1515 ----
    if (ParallelGCThreads == 0) {
      FLAG_SET_DEFAULT(ParallelGCThreads,
                       Abstract_VM_Version::parallel_worker_threads());
    }
  
!   // MarkStackSize will be set (if it hasn't been set by the user)
!   // when concurrent marking is initialized.
!   // Its value will be based upon the number of parallel marking threads.
!   // But we do set the maximum mark stack size here.
!   if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
!     FLAG_SET_DEFAULT(MarkStackSizeMax, 128 * TASKQUEUE_SIZE);
    }
  
    if (FLAG_IS_DEFAULT(GCTimeRatio) || GCTimeRatio == 0) {
      // In G1, we want the default GC overhead goal to be higher than
      // say in PS. So we set it here to 10%. Otherwise the heap might
*** 1518,1527 ****
--- 1517,1532 ----
      // fact, even 10% seems to not be high enough in some cases
      // (especially small GC stress tests that the main thing they do
      // is allocation). We might consider increase it further.
      FLAG_SET_DEFAULT(GCTimeRatio, 9);
    }
+ 
+   if (PrintGCDetails && Verbose) {
+     tty->print_cr("MarkStackSize: %uk  MarkStackSizeMax: %uk",
+       MarkStackSize / K, MarkStackSizeMax / K);
+     tty->print_cr("ConcGCThreads: %u", ConcGCThreads);
+   }
  }
  
  void Arguments::set_heap_size() {
    if (!FLAG_IS_DEFAULT(DefaultMaxRAMFraction)) {
      // Deprecated flag
*** 1976,1985 ****
--- 1981,1993 ----
    status = status && verify_object_alignment();
  
    status = status && verify_min_value(ClassMetaspaceSize, 1*M,
                                        "ClassMetaspaceSize");
  
+   status = status && verify_interval(MarkStackSizeMax,
+                                   1, (max_jint - 1), "MarkStackSizeMax");
+ 
  #ifdef SPARC
    if (UseConcMarkSweepGC || UseG1GC) {
      // Issue a stern warning if the user has explicitly set
      // UseMemSetInBOT (it is known to cause issues), but allow
      // use for experimentation and debugging.