jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/heapRegionSeq.hpp@191174b49bec (annotated)

src/share/vm/gc_implementation/g1/heapRegionSeq.hpp@191174b49bec (annotated)

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

Mon, 24 Mar 2014 15:30:14 +0100

author: tschatzl
date: Mon, 24 Mar 2014 15:30:14 +0100
changeset 6402: 191174b49bec
parent 6198: 55fb97c4c58d
child 6876: 710a3c8b516e
child 7049: eec72fa4b108
permissions: -rw-r--r--

8035406: Improve data structure for Code Cache remembered sets
Summary: Change the code cache remembered sets data structure from a GrowableArray to a chunked list of nmethods. This makes the data structure more amenable to parallelization, and decreases freeing time.
Reviewed-by: mgerdin, brutisso

 /*
  * Copyright (c) 2001, 2013, 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
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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
 #include "gc_implementation/g1/g1BiasedArray.hpp"
 class HeapRegion;
 class HeapRegionClosure;
 class FreeRegionList;
 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> {
  protected:
    virtual HeapRegion* default_value() const { return NULL; }
 };
 // This class keeps track of the region metadata (i.e., HeapRegion
 // instances). They are kept in the _regions array in address
 // order. A region's index in the array corresponds to its index in
 // the heap (i.e., 0 is the region at the bottom of the heap, 1 is
 // the one after it, etc.). Two regions that are consecutive in the
 // array should also be adjacent in the address space (i.e.,
 // region(i).end() == region(i+1).bottom().
 //
 // We create a HeapRegion when we commit the region's address space
 // for the first time. When we uncommit the address space of a
 // region we retain the HeapRegion to be able to re-use it in the
 // future (in case we recommit it).
 //
 // We keep track of three lengths:
 //
 // * _committed_length (returned by length()) is the number of currently
 //   committed regions.
 // * _allocated_length (not exposed outside this class) is the
 //   number of regions for which we have HeapRegions.
 // * max_length() returns the maximum number of regions the heap can have.
 //
 // and maintain that: _committed_length <= _allocated_length <= max_length()
 class HeapRegionSeq: public CHeapObj<mtGC> {
   friend class VMStructs;
   G1HeapRegionTable _regions;
   // The number of regions committed in the heap.
   uint _committed_length;
   // A hint for which index to start searching from for humongous
   // allocations.
   uint _next_search_index;
   // The number of regions for which we have allocated HeapRegions for.
   uint _allocated_length;
   // Find a contiguous set of empty regions of length num, starting
   // from the given index.
   uint find_contiguous_from(uint from, uint num);
   void increment_allocated_length() {
     assert(_allocated_length < max_length(), "pre-condition");
     _allocated_length++;
   }
   void increment_length() {
     assert(length() < max_length(), "pre-condition");
     _committed_length++;
   }
   void decrement_length() {
     assert(length() > 0, "pre-condition");
     _committed_length--;
   }
   HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }
   HeapWord* heap_end() const {return _regions.end_address_mapped(); }
  public:
   // Empty contructor, we'll initialize it with the initialize() method.
   HeapRegionSeq() : _regions(), _committed_length(0), _next_search_index(0), _allocated_length(0) { }
   void initialize(HeapWord* bottom, HeapWord* end);
   // Return the HeapRegion at the given index. Assume that the index
   // is valid.
   inline HeapRegion* at(uint index) const;
   // If addr is within the committed space return its corresponding
   // HeapRegion, otherwise return NULL.
   inline HeapRegion* addr_to_region(HeapWord* addr) const;
   // Return the HeapRegion that corresponds to the given
   // address. Assume the address is valid.
   inline HeapRegion* addr_to_region_unsafe(HeapWord* addr) const;
   // Return the number of regions that have been committed in the heap.
   uint length() const { return _committed_length; }
   // Return the maximum number of regions in the heap.
   uint max_length() const { return (uint)_regions.length(); }
   // Expand the sequence to reflect that the heap has grown from
   // old_end to new_end. Either create new HeapRegions, or re-use
   // existing ones, and return them in the given list. Returns the
   // memory region that covers the newly-created regions. If a
   // HeapRegion allocation fails, the result memory region might be
   // smaller than the desired one.
   MemRegion expand_by(HeapWord* old_end, HeapWord* new_end,
                       FreeRegionList* list);
   // Return the number of contiguous regions at the end of the sequence
   // that are available for allocation.
   uint free_suffix();
   // Find a contiguous set of empty regions of length num and return
   // the index of the first region or G1_NULL_HRS_INDEX if the
   // search was unsuccessful.
   uint find_contiguous(uint num);
   // Apply blk->doHeapRegion() on all committed regions in address order,
   // terminating the iteration early if doHeapRegion() returns true.
   void iterate(HeapRegionClosure* blk) const;
   // As above, but start the iteration from hr and loop around. If hr
   // is NULL, we start from the first region in the heap.
   void iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const;
   // Tag as uncommitted as many regions that are completely free as
   // possible, up to num_regions_to_remove, from the suffix of the committed
   // sequence. Return the actual number of removed regions.
   uint shrink_by(uint num_regions_to_remove);
   // Do some sanity checking.
   void verify_optional() PRODUCT_RETURN;
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP

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src/share/vm/gc_implementation/g1/heapRegionSeq.hpp@191174b49bec (annotated)

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