jdk8-mips64-public/hotspot: src/share/vm/gc_interface/collectedHeap.hpp@39b01ab7035a (annotated)

src/share/vm/gc_interface/collectedHeap.hpp@39b01ab7035a (annotated)

src/share/vm/gc_interface/collectedHeap.hpp

Fri, 16 Oct 2009 02:05:46 -0700

author: ysr
date: Fri, 16 Oct 2009 02:05:46 -0700
changeset 1462: 39b01ab7035a
parent 1428: 54b3b351d6f9
child 1600: 2dd52dea6d28
permissions: -rw-r--r--

6888898: CMS: ReduceInitialCardMarks unsafe in the presence of cms precleaning
6889757: G1: enable card mark elision for initializing writes from compiled code (ReduceInitialCardMarks)
Summary: Defer the (compiler-elided) card-mark upon a slow-path allocation until after the store and before the next subsequent safepoint; G1 now answers yes to can_elide_tlab_write_barriers().
Reviewed-by: jcoomes, kvn, never

 /*
  * Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 // A "CollectedHeap" is an implementation of a java heap for HotSpot.  This
 // is an abstract class: there may be many different kinds of heaps.  This
 // class defines the functions that a heap must implement, and contains
 // infrastructure common to all heaps.
 class BarrierSet;
 class ThreadClosure;
 class AdaptiveSizePolicy;
 class Thread;
 //
 // CollectedHeap
 //   SharedHeap
 //     GenCollectedHeap
 //     G1CollectedHeap
 //   ParallelScavengeHeap
 //
 class CollectedHeap : public CHeapObj {
   friend class VMStructs;
   friend class IsGCActiveMark; // Block structured external access to _is_gc_active
   friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe
 #ifdef ASSERT
   static int       _fire_out_of_memory_count;
 #endif
   // Used for filler objects (static, but initialized in ctor).
   static size_t _filler_array_max_size;
  protected:
   MemRegion _reserved;
   BarrierSet* _barrier_set;
   bool _is_gc_active;
   unsigned int _total_collections;          // ... started
   unsigned int _total_full_collections;     // ... started
   NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
   NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
   // Reason for current garbage collection.  Should be set to
   // a value reflecting no collection between collections.
   GCCause::Cause _gc_cause;
   GCCause::Cause _gc_lastcause;
   PerfStringVariable* _perf_gc_cause;
   PerfStringVariable* _perf_gc_lastcause;
   // Constructor
   CollectedHeap();
   // Create a new tlab
   virtual HeapWord* allocate_new_tlab(size_t size);
   // Fix up tlabs to make the heap well-formed again,
   // optionally retiring the tlabs.
   virtual void fill_all_tlabs(bool retire);
   // Accumulate statistics on all tlabs.
   virtual void accumulate_statistics_all_tlabs();
   // Reinitialize tlabs before resuming mutators.
   virtual void resize_all_tlabs();
  protected:
   // Allocate from the current thread's TLAB, with broken-out slow path.
   inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size);
   static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size);
   // Allocate an uninitialized block of the given size, or returns NULL if
   // this is impossible.
   inline static HeapWord* common_mem_allocate_noinit(size_t size, bool is_noref, TRAPS);
   // Like allocate_init, but the block returned by a successful allocation
   // is guaranteed initialized to zeros.
   inline static HeapWord* common_mem_allocate_init(size_t size, bool is_noref, TRAPS);
   // Same as common_mem version, except memory is allocated in the permanent area
   // If there is no permanent area, revert to common_mem_allocate_noinit
   inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS);
   // Same as common_mem version, except memory is allocated in the permanent area
   // If there is no permanent area, revert to common_mem_allocate_init
   inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS);
   // Helper functions for (VM) allocation.
   inline static void post_allocation_setup_common(KlassHandle klass,
                                                   HeapWord* obj, size_t size);
   inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
                                                             HeapWord* objPtr,
                                                             size_t size);
   inline static void post_allocation_setup_obj(KlassHandle klass,
                                                HeapWord* obj, size_t size);
   inline static void post_allocation_setup_array(KlassHandle klass,
                                                  HeapWord* obj, size_t size,
                                                  int length);
   // Clears an allocated object.
   inline static void init_obj(HeapWord* obj, size_t size);
   // Filler object utilities.
   static inline size_t filler_array_hdr_size();
   static inline size_t filler_array_min_size();
   static inline size_t filler_array_max_size();
   DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
   DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words);)
   // Fill with a single array; caller must ensure filler_array_min_size() <=
   // words <= filler_array_max_size().
   static inline void fill_with_array(HeapWord* start, size_t words);
   // Fill with a single object (either an int array or a java.lang.Object).
   static inline void fill_with_object_impl(HeapWord* start, size_t words);
   // Verification functions
   virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
     PRODUCT_RETURN;
   virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
     PRODUCT_RETURN;
   debug_only(static void check_for_valid_allocation_state();)
  public:
   enum Name {
     Abstract,
     SharedHeap,
     GenCollectedHeap,
     ParallelScavengeHeap,
     G1CollectedHeap
   };
   virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
   /**
    * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
    * and JNI_OK on success.
    */
   virtual jint initialize() = 0;
   // In many heaps, there will be a need to perform some initialization activities
   // after the Universe is fully formed, but before general heap allocation is allowed.
   // This is the correct place to place such initialization methods.
   virtual void post_initialize() = 0;
   MemRegion reserved_region() const { return _reserved; }
   address base() const { return (address)reserved_region().start(); }
   // Future cleanup here. The following functions should specify bytes or
   // heapwords as part of their signature.
   virtual size_t capacity() const = 0;
   virtual size_t used() const = 0;
   // Return "true" if the part of the heap that allocates Java
   // objects has reached the maximal committed limit that it can
   // reach, without a garbage collection.
   virtual bool is_maximal_no_gc() const = 0;
   virtual size_t permanent_capacity() const = 0;
   virtual size_t permanent_used() const = 0;
   // Support for java.lang.Runtime.maxMemory():  return the maximum amount of
   // memory that the vm could make available for storing 'normal' java objects.
   // This is based on the reserved address space, but should not include space
   // that the vm uses internally for bookkeeping or temporary storage (e.g.,
   // perm gen space or, in the case of the young gen, one of the survivor
   // spaces).
   virtual size_t max_capacity() const = 0;
   // Returns "TRUE" if "p" points into the reserved area of the heap.
   bool is_in_reserved(const void* p) const {
     return _reserved.contains(p);
   }
   bool is_in_reserved_or_null(const void* p) const {
     return p == NULL || is_in_reserved(p);
   }
   // Returns "TRUE" if "p" points to the head of an allocated object in the
   // heap. Since this method can be expensive in general, we restrict its
   // use to assertion checking only.
   virtual bool is_in(const void* p) const = 0;
   bool is_in_or_null(const void* p) const {
     return p == NULL || is_in(p);
   }
   // Let's define some terms: a "closed" subset of a heap is one that
   //
   // 1) contains all currently-allocated objects, and
   //
   // 2) is closed under reference: no object in the closed subset
   //    references one outside the closed subset.
   //
   // Membership in a heap's closed subset is useful for assertions.
   // Clearly, the entire heap is a closed subset, so the default
   // implementation is to use "is_in_reserved".  But this may not be too
   // liberal to perform useful checking.  Also, the "is_in" predicate
   // defines a closed subset, but may be too expensive, since "is_in"
   // verifies that its argument points to an object head.  The
   // "closed_subset" method allows a heap to define an intermediate
   // predicate, allowing more precise checking than "is_in_reserved" at
   // lower cost than "is_in."
   // One important case is a heap composed of disjoint contiguous spaces,
   // such as the Garbage-First collector.  Such heaps have a convenient
   // closed subset consisting of the allocated portions of those
   // contiguous spaces.
   // Return "TRUE" iff the given pointer points into the heap's defined
   // closed subset (which defaults to the entire heap).
   virtual bool is_in_closed_subset(const void* p) const {
     return is_in_reserved(p);
   }
   bool is_in_closed_subset_or_null(const void* p) const {
     return p == NULL || is_in_closed_subset(p);
   }
   // XXX is_permanent() and is_in_permanent() should be better named
   // to distinguish one from the other.
   // Returns "TRUE" if "p" is allocated as "permanent" data.
   // If the heap does not use "permanent" data, returns the same
   // value is_in_reserved() would return.
   // NOTE: this actually returns true if "p" is in reserved space
   // for the space not that it is actually allocated (i.e. in committed
   // space). If you need the more conservative answer use is_permanent().
   virtual bool is_in_permanent(const void *p) const = 0;
   bool is_in_permanent_or_null(const void *p) const {
     return p == NULL || is_in_permanent(p);
   }
   // Returns "TRUE" if "p" is in the committed area of  "permanent" data.
   // If the heap does not use "permanent" data, returns the same
   // value is_in() would return.
   virtual bool is_permanent(const void *p) const = 0;
   bool is_permanent_or_null(const void *p) const {
     return p == NULL || is_permanent(p);
   }
   // An object is scavengable if its location may move during a scavenge.
   // (A scavenge is a GC which is not a full GC.)
   // Currently, this just means it is not perm (and not null).
   // This could change if we rethink what's in perm-gen.
   bool is_scavengable(const void *p) const {
     return !is_in_permanent_or_null(p);
   }
   // Returns "TRUE" if "p" is a method oop in the
   // current heap, with high probability. This predicate
   // is not stable, in general.
   bool is_valid_method(oop p) const;
   void set_gc_cause(GCCause::Cause v) {
      if (UsePerfData) {
        _gc_lastcause = _gc_cause;
        _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
        _perf_gc_cause->set_value(GCCause::to_string(v));
      }
     _gc_cause = v;
   }
   GCCause::Cause gc_cause() { return _gc_cause; }
   // Preload classes into the shared portion of the heap, and then dump
   // that data to a file so that it can be loaded directly by another
   // VM (then terminate).
   virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); }
   // General obj/array allocation facilities.
   inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
   inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
   inline static oop large_typearray_allocate(KlassHandle klass, int size, int length, TRAPS);
   // Special obj/array allocation facilities.
   // Some heaps may want to manage "permanent" data uniquely. These default
   // to the general routines if the heap does not support such handling.
   inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS);
   // permanent_obj_allocate_no_klass_install() does not do the installation of
   // the klass pointer in the newly created object (as permanent_obj_allocate()
   // above does).  This allows for a delay in the installation of the klass
   // pointer that is needed during the create of klassKlass's.  The
   // method post_allocation_install_obj_klass() is used to install the
   // klass pointer.
   inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass,
                                                             int size,
                                                             TRAPS);
   inline static void post_allocation_install_obj_klass(KlassHandle klass,
                                                        oop obj,
                                                        int size);
   inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS);
   // Raw memory allocation facilities
   // The obj and array allocate methods are covers for these methods.
   // The permanent allocation method should default to mem_allocate if
   // permanent memory isn't supported.
   virtual HeapWord* mem_allocate(size_t size,
                                  bool is_noref,
                                  bool is_tlab,
                                  bool* gc_overhead_limit_was_exceeded) = 0;
   virtual HeapWord* permanent_mem_allocate(size_t size) = 0;
   // The boundary between a "large" and "small" array of primitives, in words.
   virtual size_t large_typearray_limit() = 0;
   // Utilities for turning raw memory into filler objects.
   //
   // min_fill_size() is the smallest region that can be filled.
   // fill_with_objects() can fill arbitrary-sized regions of the heap using
   // multiple objects.  fill_with_object() is for regions known to be smaller
   // than the largest array of integers; it uses a single object to fill the
   // region and has slightly less overhead.
   static size_t min_fill_size() {
     return size_t(align_object_size(oopDesc::header_size()));
   }
   static void fill_with_objects(HeapWord* start, size_t words);
   static void fill_with_object(HeapWord* start, size_t words);
   static void fill_with_object(MemRegion region) {
     fill_with_object(region.start(), region.word_size());
   }
   static void fill_with_object(HeapWord* start, HeapWord* end) {
     fill_with_object(start, pointer_delta(end, start));
   }
   // Some heaps may offer a contiguous region for shared non-blocking
   // allocation, via inlined code (by exporting the address of the top and
   // end fields defining the extent of the contiguous allocation region.)
   // This function returns "true" iff the heap supports this kind of
   // allocation.  (Default is "no".)
   virtual bool supports_inline_contig_alloc() const {
     return false;
   }
   // These functions return the addresses of the fields that define the
   // boundaries of the contiguous allocation area.  (These fields should be
   // physically near to one another.)
   virtual HeapWord** top_addr() const {
     guarantee(false, "inline contiguous allocation not supported");
     return NULL;
   }
   virtual HeapWord** end_addr() const {
     guarantee(false, "inline contiguous allocation not supported");
     return NULL;
   }
   // Some heaps may be in an unparseable state at certain times between
   // collections. This may be necessary for efficient implementation of
   // certain allocation-related activities. Calling this function before
   // attempting to parse a heap ensures that the heap is in a parsable
   // state (provided other concurrent activity does not introduce
   // unparsability). It is normally expected, therefore, that this
   // method is invoked with the world stopped.
   // NOTE: if you override this method, make sure you call
   // super::ensure_parsability so that the non-generational
   // part of the work gets done. See implementation of
   // CollectedHeap::ensure_parsability and, for instance,
   // that of GenCollectedHeap::ensure_parsability().
   // The argument "retire_tlabs" controls whether existing TLABs
   // are merely filled or also retired, thus preventing further
   // allocation from them and necessitating allocation of new TLABs.
   virtual void ensure_parsability(bool retire_tlabs);
   // Return an estimate of the maximum allocation that could be performed
   // without triggering any collection or expansion activity.  In a
   // generational collector, for example, this is probably the largest
   // allocation that could be supported (without expansion) in the youngest
   // generation.  It is "unsafe" because no locks are taken; the result
   // should be treated as an approximation, not a guarantee, for use in
   // heuristic resizing decisions.
   virtual size_t unsafe_max_alloc() = 0;
   // Section on thread-local allocation buffers (TLABs)
   // If the heap supports thread-local allocation buffers, it should override
   // the following methods:
   // Returns "true" iff the heap supports thread-local allocation buffers.
   // The default is "no".
   virtual bool supports_tlab_allocation() const {
     return false;
   }
   // The amount of space available for thread-local allocation buffers.
   virtual size_t tlab_capacity(Thread *thr) const {
     guarantee(false, "thread-local allocation buffers not supported");
     return 0;
   }
   // An estimate of the maximum allocation that could be performed
   // for thread-local allocation buffers without triggering any
   // collection or expansion activity.
   virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
     guarantee(false, "thread-local allocation buffers not supported");
     return 0;
   }
   // Can a compiler initialize a new object without store barriers?
   // This permission only extends from the creation of a new object
   // via a TLAB up to the first subsequent safepoint. If such permission
   // is granted for this heap type, the compiler promises to call
   // defer_store_barrier() below on any slow path allocation of
   // a new object for which such initializing store barriers will
   // have been elided.
   virtual bool can_elide_tlab_store_barriers() const = 0;
   // If a compiler is eliding store barriers for TLAB-allocated objects,
   // there is probably a corresponding slow path which can produce
   // an object allocated anywhere.  The compiler's runtime support
   // promises to call this function on such a slow-path-allocated
   // object before performing initializations that have elided
   // store barriers. Returns new_obj, or maybe a safer copy thereof.
   virtual oop defer_store_barrier(JavaThread* thread, oop new_obj);
   // Answers whether an initializing store to a new object currently
   // allocated at the given address doesn't need a (deferred) store
   // barrier. Returns "true" if it doesn't need an initializing
   // store barrier; answers "false" if it does.
   virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;
   // If the CollectedHeap was asked to defer a store barrier above,
   // this informs it to flush such a deferred store barrier to the
   // remembered set.
   virtual void flush_deferred_store_barrier(JavaThread* thread);
   // Can a compiler elide a store barrier when it writes
   // a permanent oop into the heap?  Applies when the compiler
   // is storing x to the heap, where x->is_perm() is true.
   virtual bool can_elide_permanent_oop_store_barriers() const = 0;
   // Does this heap support heap inspection (+PrintClassHistogram?)
   virtual bool supports_heap_inspection() const = 0;
   // Perform a collection of the heap; intended for use in implementing
   // "System.gc".  This probably implies as full a collection as the
   // "CollectedHeap" supports.
   virtual void collect(GCCause::Cause cause) = 0;
   // This interface assumes that it's being called by the
   // vm thread. It collects the heap assuming that the
   // heap lock is already held and that we are executing in
   // the context of the vm thread.
   virtual void collect_as_vm_thread(GCCause::Cause cause) = 0;
   // Returns the barrier set for this heap
   BarrierSet* barrier_set() { return _barrier_set; }
   // Returns "true" iff there is a stop-world GC in progress.  (I assume
   // that it should answer "false" for the concurrent part of a concurrent
   // collector -- dld).
   bool is_gc_active() const { return _is_gc_active; }
   // Total number of GC collections (started)
   unsigned int total_collections() const { return _total_collections; }
   unsigned int total_full_collections() const { return _total_full_collections;}
   // Increment total number of GC collections (started)
   // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
   void increment_total_collections(bool full = false) {
     _total_collections++;
     if (full) {
       increment_total_full_collections();
     }
   }
   void increment_total_full_collections() { _total_full_collections++; }
   // Return the AdaptiveSizePolicy for the heap.
   virtual AdaptiveSizePolicy* size_policy() = 0;
   // Iterate over all the ref-containing fields of all objects, calling
   // "cl.do_oop" on each. This includes objects in permanent memory.
   virtual void oop_iterate(OopClosure* cl) = 0;
   // Iterate over all objects, calling "cl.do_object" on each.
   // This includes objects in permanent memory.
   virtual void object_iterate(ObjectClosure* cl) = 0;
   // Similar to object_iterate() except iterates only
   // over live objects.
   virtual void safe_object_iterate(ObjectClosure* cl) = 0;
   // Behaves the same as oop_iterate, except only traverses
   // interior pointers contained in permanent memory. If there
   // is no permanent memory, does nothing.
   virtual void permanent_oop_iterate(OopClosure* cl) = 0;
   // Behaves the same as object_iterate, except only traverses
   // object contained in permanent memory. If there is no
   // permanent memory, does nothing.
   virtual void permanent_object_iterate(ObjectClosure* cl) = 0;
   // NOTE! There is no requirement that a collector implement these
   // functions.
   //
   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
   // each address in the (reserved) heap is a member of exactly
   // one block.  The defining characteristic of a block is that it is
   // possible to find its size, and thus to progress forward to the next
   // block.  (Blocks may be of different sizes.)  Thus, blocks may
   // represent Java objects, or they might be free blocks in a
   // free-list-based heap (or subheap), as long as the two kinds are
   // distinguishable and the size of each is determinable.
   // Returns the address of the start of the "block" that contains the
   // address "addr".  We say "blocks" instead of "object" since some heaps
   // may not pack objects densely; a chunk may either be an object or a
   // non-object.
   virtual HeapWord* block_start(const void* addr) const = 0;
   // Requires "addr" to be the start of a chunk, and returns its size.
   // "addr + size" is required to be the start of a new chunk, or the end
   // of the active area of the heap.
   virtual size_t block_size(const HeapWord* addr) const = 0;
   // Requires "addr" to be the start of a block, and returns "TRUE" iff
   // the block is an object.
   virtual bool block_is_obj(const HeapWord* addr) const = 0;
   // Returns the longest time (in ms) that has elapsed since the last
   // time that any part of the heap was examined by a garbage collection.
   virtual jlong millis_since_last_gc() = 0;
   // Perform any cleanup actions necessary before allowing a verification.
   virtual void prepare_for_verify() = 0;
   // Generate any dumps preceding or following a full gc
   void pre_full_gc_dump();
   void post_full_gc_dump();
   virtual void print() const = 0;
   virtual void print_on(outputStream* st) const = 0;
   // Print all GC threads (other than the VM thread)
   // used by this heap.
   virtual void print_gc_threads_on(outputStream* st) const = 0;
   void print_gc_threads() { print_gc_threads_on(tty); }
   // Iterator for all GC threads (other than VM thread)
   virtual void gc_threads_do(ThreadClosure* tc) const = 0;
   // Print any relevant tracing info that flags imply.
   // Default implementation does nothing.
   virtual void print_tracing_info() const = 0;
   // Heap verification
   virtual void verify(bool allow_dirty, bool silent, bool option) = 0;
   // Non product verification and debugging.
 #ifndef PRODUCT
   // Support for PromotionFailureALot.  Return true if it's time to cause a
   // promotion failure.  The no-argument version uses
   // this->_promotion_failure_alot_count as the counter.
   inline bool promotion_should_fail(volatile size_t* count);
   inline bool promotion_should_fail();
   // Reset the PromotionFailureALot counters.  Should be called at the end of a
   // GC in which promotion failure ocurred.
   inline void reset_promotion_should_fail(volatile size_t* count);
   inline void reset_promotion_should_fail();
 #endif  // #ifndef PRODUCT
 #ifdef ASSERT
   static int fired_fake_oom() {
     return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
   }
 #endif
 };
 // Class to set and reset the GC cause for a CollectedHeap.
 class GCCauseSetter : StackObj {
   CollectedHeap* _heap;
   GCCause::Cause _previous_cause;
  public:
   GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
     assert(SafepointSynchronize::is_at_safepoint(),
            "This method manipulates heap state without locking");
     _heap = heap;
     _previous_cause = _heap->gc_cause();
     _heap->set_gc_cause(cause);
   }
   ~GCCauseSetter() {
     assert(SafepointSynchronize::is_at_safepoint(),
           "This method manipulates heap state without locking");
     _heap->set_gc_cause(_previous_cause);
   }
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_interface/collectedHeap.hpp@39b01ab7035a (annotated)

src/share/vm/gc_interface/collectedHeap.hpp