src/share/vm/memory/virtualspace.cpp

@@ -33,14 +33,14 @@
 
 // ReservedSpace
 
 // Dummy constructor
 ReservedSpace::ReservedSpace() : _base(NULL), _size(0), _noaccess_prefix(0),
-    _alignment(0), _special(false), _executable(false) {
+    _alignment(0), _special(false), _executable(false), _backing_fd(-1) {
 }
 
-ReservedSpace::ReservedSpace(size_t size, size_t preferred_page_size) {
+ReservedSpace::ReservedSpace(size_t size, size_t preferred_page_size) : _backing_fd(-1) {
   bool has_preferred_page_size = preferred_page_size != 0;
   // Want to use large pages where possible and pad with small pages.
   size_t page_size = has_preferred_page_size ? preferred_page_size : os::page_size_for_region_unaligned(size, 1);
   bool large_pages = page_size != (size_t)os::vm_page_size();
   size_t alignment;

@@ -57,17 +57,17 @@
   initialize(size, alignment, large_pages, NULL, false);
 }
 
 ReservedSpace::ReservedSpace(size_t size, size_t alignment,
                              bool large,
-                             char* requested_address) {
+                             char* requested_address) : _backing_fd(-1) {
   initialize(size, alignment, large, requested_address, false);
 }
 
 ReservedSpace::ReservedSpace(size_t size, size_t alignment,
                              bool large,
-                             bool executable) {
+                             bool executable) : _backing_fd(-1) {
   initialize(size, alignment, large, NULL, executable);
 }
 
 // Helper method.
 static bool failed_to_reserve_as_requested(char* base, char* requested_address,

@@ -118,11 +118,13 @@
     return;
   }
 
   // If OS doesn't support demand paging for large page memory, we need
   // to use reserve_memory_special() to reserve and pin the entire region.
-  bool special = large && !os::can_commit_large_page_memory();
+  // If there is a backing file directory for this VirtualSpace then whether largepages are allocated is upto the filesystem the dir resides in.
+  // So we ignore the UseLargePages flag in this case.
+  bool special = (_backing_fd == -1) && (large && !os::can_commit_large_page_memory());
   char* base = NULL;
 
   if (special) {
 
     base = os::reserve_memory_special(size, alignment, requested_address, executable);

@@ -155,28 +157,33 @@
     // If the memory was requested at a particular address, use
     // os::attempt_reserve_memory_at() to avoid over mapping something
     // important.  If available space is not detected, return NULL.
 
     if (requested_address != 0) {
-      base = os::attempt_reserve_memory_at(size, requested_address);
+      base = os::attempt_reserve_memory_at(size, requested_address, _backing_fd);
       if (failed_to_reserve_as_requested(base, requested_address, size, false)) {
         // OS ignored requested address. Try different address.
         base = NULL;
       }
     } else {
-      base = os::reserve_memory(size, NULL, alignment);
+      base = os::reserve_memory(size, NULL, alignment, _backing_fd);
     }
 
     if (base == NULL) return;
 
     // Check alignment constraints
     if ((((size_t)base) & (alignment - 1)) != 0) {
       // Base not aligned, retry
+      if (_backing_fd != -1) {
+        if (!os::unmap_memory(base, size)) fatal("os::release_memory failed");
+      }
+      else {
       if (!os::release_memory(base, size)) fatal("os::release_memory failed");
+      }
       // Make sure that size is aligned
       size = align_size_up(size, alignment);
-      base = os::reserve_memory_aligned(size, alignment);
+      base = os::reserve_memory_aligned(size, alignment, _backing_fd);
 
       if (requested_address != 0 &&
           failed_to_reserve_as_requested(base, requested_address, size, false)) {
         // As a result of the alignment constraints, the allocated base differs
         // from the requested address. Return back to the caller who can

@@ -188,10 +195,14 @@
   }
   // Done
   _base = base;
   _size = size;
   _alignment = alignment;
+  // If heap is reserved with a backing file, the entire space has been committed. So set the _special flag to true
+  if (_backing_fd != -1) {
+    _special = true;
+  }
 }
 
 
 ReservedSpace::ReservedSpace(char* base, size_t size, size_t alignment,
                              bool special, bool executable) {

@@ -311,11 +322,13 @@
     release();
   }
 
   // If OS doesn't support demand paging for large page memory, we need
   // to use reserve_memory_special() to reserve and pin the entire region.
-  bool special = large && !os::can_commit_large_page_memory();
+  // If there is a backing file directory for this VirtualSpace then whether largepages are allocated is upto the filesystem the dir resides in.
+  // So we ignore the UseLargePages flag in this case.
+  bool special = (_backing_fd == -1) && (large && !os::can_commit_large_page_memory());
   char* base = NULL;
 
   log_trace(gc, heap, coops)("Trying to allocate at address " PTR_FORMAT
                              " heap of size " SIZE_FORMAT_HEX,
                              p2i(requested_address),

@@ -348,21 +361,25 @@
     // If the memory was requested at a particular address, use
     // os::attempt_reserve_memory_at() to avoid over mapping something
     // important.  If available space is not detected, return NULL.
 
     if (requested_address != 0) {
-      base = os::attempt_reserve_memory_at(size, requested_address);
+      base = os::attempt_reserve_memory_at(size, requested_address, _backing_fd);
     } else {
-      base = os::reserve_memory(size, NULL, alignment);
+      base = os::reserve_memory(size, NULL, alignment, _backing_fd);
     }
   }
   if (base == NULL) { return; }
 
   // Done
   _base = base;
   _size = size;
   _alignment = alignment;
+  // If heap is reserved with a backing file, the entire space has been committed. So set the _special flag to true
+  if (_backing_fd != -1) {
+    _special = true;
+  }
 
   // Check alignment constraints
   if ((((size_t)base) & (alignment - 1)) != 0) {
     // Base not aligned, retry.
     release();

@@ -554,16 +571,20 @@
       initialize(size + noaccess_prefix, alignment, large, NULL, false);
     }
   }
 }
 
-ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment, bool large) : ReservedSpace() {
+ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment, bool large, const char* backingFSforHeap) : ReservedSpace() {
 
   if (size == 0) {
     return;
   }
 
+  if (backingFSforHeap != NULL) {
+    _backing_fd = os::create_file_for_heap(backingFSforHeap, size);
+  }
+
   // Heap size should be aligned to alignment, too.
   guarantee(is_size_aligned(size, alignment), "set by caller");
 
   if (UseCompressedOops) {
     initialize_compressed_heap(size, alignment, large);

@@ -583,10 +604,14 @@
          "area must be distinguishable from marks for mark-sweep");
 
   if (base() > 0) {
     MemTracker::record_virtual_memory_type((address)base(), mtJavaHeap);
   }
+
+  if (backingFSforHeap != NULL) {
+    os::close(_backing_fd);
+  }
 }
 
 // Reserve space for code segment.  Same as Java heap only we mark this as
 // executable.
 ReservedCodeSpace::ReservedCodeSpace(size_t r_size,