jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1AllocRegion.hpp@abdfc822206f (annotated)

src/share/vm/gc_implementation/g1/g1AllocRegion.hpp@abdfc822206f (annotated)

src/share/vm/gc_implementation/g1/g1AllocRegion.hpp

Wed, 30 Mar 2011 10:26:59 -0400

author: tonyp
date: Wed, 30 Mar 2011 10:26:59 -0400
changeset 2715: abdfc822206f
child 3028: f44782f04dd4
permissions: -rw-r--r--

7023069: G1: Introduce symmetric locking in the slow allocation path
7023151: G1: refactor the code that operates on _cur_alloc_region to be re-used for allocs by the GC threads
7018286: G1: humongous allocation attempts should take the GC locker into account
Summary: First, this change replaces the asymmetric locking scheme in the G1 slow alloc path by a summetric one. Second, it factors out the code that operates on _cur_alloc_region so that it can be re-used for allocations by the GC threads in the future.
Reviewed-by: stefank, brutisso, johnc

 /*
  * Copyright (c) 2011, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP
 #include "gc_implementation/g1/heapRegion.hpp"
 class G1CollectedHeap;
 // 0 -> no tracing, 1 -> basic tracing, 2 -> basic + allocation tracing
 #define G1_ALLOC_REGION_TRACING 0
 class ar_ext_msg;
 // A class that holds a region that is active in satisfying allocation
 // requests, potentially issued in parallel. When the active region is
 // full it will be retired it replaced with a new one. The
 // implementation assumes that fast-path allocations will be lock-free
 // and a lock will need to be taken when the active region needs to be
 // replaced.
 class G1AllocRegion VALUE_OBJ_CLASS_SPEC {
   friend class ar_ext_msg;
 private:
   // The active allocating region we are currently allocating out
   // of. The invariant is that if this object is initialized (i.e.,
   // init() has been called and release() has not) then _alloc_region
   // is either an active allocating region or the dummy region (i.e.,
   // it can never be NULL) and this object can be used to satisfy
   // allocation requests. If this object is not initialized
   // (i.e. init() has not been called or release() has been called)
   // then _alloc_region is NULL and this object should not be used to
   // satisfy allocation requests (it was done this way to force the
   // correct use of init() and release()).
   HeapRegion* _alloc_region;
   // When we set up a new active region we save its used bytes in this
   // field so that, when we retire it, we can calculate how much space
   // we allocated in it.
   size_t _used_bytes_before;
   // Specifies whether the allocate calls will do BOT updates or not.
   bool _bot_updates;
   // Useful for debugging and tracing.
   const char* _name;
   // A dummy region (i.e., it's been allocated specially for this
   // purpose and it is not part of the heap) that is full (i.e., top()
   // == end()). When we don't have a valid active region we make
   // _alloc_region point to this. This allows us to skip checking
   // whether the _alloc_region is NULL or not.
   static HeapRegion* _dummy_region;
   // Some of the methods below take a bot_updates parameter. Its value
   // should be the same as the _bot_updates field. The idea is that
   // the parameter will be a constant for a particular alloc region
   // and, given that these methods will be hopefully inlined, the
   // compiler should compile out the test.
   // Perform a non-MT-safe allocation out of the given region.
   static inline HeapWord* allocate(HeapRegion* alloc_region,
                                    size_t word_size,
                                    bool bot_updates);
   // Perform a MT-safe allocation out of the given region.
   static inline HeapWord* par_allocate(HeapRegion* alloc_region,
                                        size_t word_size,
                                        bool bot_updates);
   // Ensure that the region passed as a parameter has been filled up
   // so that noone else can allocate out of it any more.
   static void fill_up_remaining_space(HeapRegion* alloc_region,
                                       bool bot_updates);
   // Retire the active allocating region. If fill_up is true then make
   // sure that the region is full before we retire it so that noone
   // else can allocate out of it.
   void retire(bool fill_up);
   // Allocate a new active region and use it to perform a word_size
   // allocation. The force parameter will be passed on to
   // G1CollectedHeap::allocate_new_alloc_region() and tells it to try
   // to allocate a new region even if the max has been reached.
   HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force);
   void fill_in_ext_msg(ar_ext_msg* msg, const char* message);
 protected:
   // For convenience as subclasses use it.
   static G1CollectedHeap* _g1h;
   virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0;
   virtual void retire_region(HeapRegion* alloc_region,
                              size_t allocated_bytes) = 0;
   G1AllocRegion(const char* name, bool bot_updates);
 public:
   static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region);
   HeapRegion* get() const {
     // Make sure that the dummy region does not escape this class.
     return (_alloc_region == _dummy_region) ? NULL : _alloc_region;
   }
   // The following two are the building blocks for the allocation method.
   // First-level allocation: Should be called without holding a
   // lock. It will try to allocate lock-free out of the active region,
   // or return NULL if it was unable to.
   inline HeapWord* attempt_allocation(size_t word_size, bool bot_updates);
   // Second-level allocation: Should be called while holding a
   // lock. It will try to first allocate lock-free out of the active
   // region or, if it's unable to, it will try to replace the active
   // alloc region with a new one. We require that the caller takes the
   // appropriate lock before calling this so that it is easier to make
   // it conform to its locking protocol.
   inline HeapWord* attempt_allocation_locked(size_t word_size,
                                              bool bot_updates);
   // Should be called to allocate a new region even if the max of this
   // type of regions has been reached. Should only be called if other
   // allocation attempts have failed and we are not holding a valid
   // active region.
   inline HeapWord* attempt_allocation_force(size_t word_size,
                                             bool bot_updates);
   // Should be called before we start using this object.
   void init();
   // Should be called when we want to release the active region which
   // is returned after it's been retired.
   HeapRegion* release();
 #if G1_ALLOC_REGION_TRACING
   void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL);
 #else // G1_ALLOC_REGION_TRACING
   void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL) { }
 #endif // G1_ALLOC_REGION_TRACING
 };
 class ar_ext_msg : public err_msg {
 public:
   ar_ext_msg(G1AllocRegion* alloc_region, const char *message) : err_msg("") {
     alloc_region->fill_in_ext_msg(this, message);
   }
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1AllocRegion.hpp@abdfc822206f (annotated)

src/share/vm/gc_implementation/g1/g1AllocRegion.hpp