WIP

Author: jsikstro

src/hotspot/share/gc/z/zPageAllocator.cpp

@@ -1102,7 +1102,9 @@ void ZPartition::free_memory_alloc_failed(ZMemoryAllocation* allocation) {
 }
 
 void ZPartition::threads_do(ThreadClosure* tc) const {
-  tc->do_thread(const_cast<ZUncommitter*>(&_uncommitter));
+  if (ZUncommitter::is_enabled()) {
+    tc->do_thread(const_cast<ZUncommitter*>(&_uncommitter));
+  }
 }
 
 void ZPartition::print_on(outputStream* st) const {
@@ -1210,7 +1212,7 @@ ZPageAllocator::ZPageAllocator(size_t min_capacity,
                                size_t max_capacity)
   : _lock(),
     _virtual(max_capacity),
-    _physical(max_capacity),
+    _physical(min_capacity, max_capacity),
     _min_capacity(min_capacity),
     _max_capacity(max_capacity),
     _used(0),
@@ -1243,9 +1245,6 @@ ZPageAllocator::ZPageAllocator(size_t min_capacity,
   // Warn if system limits could stop us from reaching max capacity
   _physical.warn_commit_limits(max_capacity);
 
-  // Check if uncommit should and can be enabled
-  _physical.try_enable_uncommit(min_capacity, max_capacity);
-
   // Successfully initialized
   _initialized = true;
 }

src/hotspot/share/gc/z/zPhysicalMemoryManager.cpp

@@ -45,7 +45,7 @@
 #include "utilities/globalDefinitions.hpp"
 #include "utilities/powerOfTwo.hpp"
 
-ZPhysicalMemoryManager::ZPhysicalMemoryManager(size_t max_capacity)
+ZPhysicalMemoryManager::ZPhysicalMemoryManager(size_t min_capacity, size_t max_capacity)
   : _backing(max_capacity),
     _physical_mappings(ZAddressOffsetMax) {
   assert(is_aligned(max_capacity, ZGranuleSize), "must be granule aligned");
@@ -77,6 +77,8 @@ ZPhysicalMemoryManager::ZPhysicalMemoryManager(size_t max_capacity)
     next_index += num_segments;
   }
 
+  try_enable_uncommit(min_capacity, max_capacity);
+
   assert(untype(next_index) == ZBackingIndexMax, "must insert all capacity");
 }
 

src/hotspot/share/gc/z/zPhysicalMemoryManager.hpp

@@ -48,13 +48,14 @@ class ZPhysicalMemoryManager {
   void copy_to_stash(ZArraySlice<zbacking_index> stash, const ZVirtualMemory& vmem) const;
   void copy_from_stash(const ZArraySlice<const zbacking_index> stash, const ZVirtualMemory& vmem);
 
+  void try_enable_uncommit(size_t min_capacity, size_t max_capacity);
+
 public:
-  ZPhysicalMemoryManager(size_t max_capacity);
+  ZPhysicalMemoryManager(size_t min_capacity, size_t max_capacity);
 
   bool is_initialized() const;
 
   void warn_commit_limits(size_t max_capacity) const;
-  void try_enable_uncommit(size_t min_capacity, size_t max_capacity);
 
   void alloc(const ZVirtualMemory& vmem, uint32_t numa_id);
   void free(const ZVirtualMemory& vmem, uint32_t numa_id);

src/hotspot/share/gc/z/zUncommitter.cpp

@@ -40,6 +40,10 @@
 
 static const ZStatCounter ZCounterUncommit("Memory", "Uncommit", ZStatUnitBytesPerSecond);
 
+bool ZUncommitter::is_enabled() {
+  return ZUncommit;
+}
+
 ZUncommitter::ZUncommitter(uint32_t id, ZPartition* partition)
   : _id(id),
     _partition(partition),
@@ -51,6 +55,12 @@ ZUncommitter::ZUncommitter(uint32_t id, ZPartition* partition)
     _cycle_start(0.0),
     _to_uncommit(0),
     _uncommitted(0) {
+  if (!is_enabled()) {
+    // Disabled, do not start.
+    _stop = true;
+    return;
+  }
+
   set_name("ZUncommitter#%u", id);
   create_and_start();
 }

src/hotspot/share/gc/z/zUncommitter.hpp

@@ -70,6 +70,8 @@ class ZUncommitter : public ZThread {
   virtual void terminate();
 
 public:
+  static bool is_enabled();
+
   ZUncommitter(uint32_t id, ZPartition* partition);
 
   void cancel_uncommit_cycle();