jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/shared/parGCAllocBuffer.hpp@aaf61e68b255 (annotated)

src/share/vm/gc_implementation/shared/parGCAllocBuffer.hpp@aaf61e68b255 (annotated)

src/share/vm/gc_implementation/shared/parGCAllocBuffer.hpp

Mon, 06 Aug 2012 12:20:14 -0700

author: johnc
date: Mon, 06 Aug 2012 12:20:14 -0700
changeset 3982: aaf61e68b255
parent 3900: src/share/vm/gc_implementation/parNew/parGCAllocBuffer.hpp@d2a62e0f25eb
child 4067: b2ef234911c9
permissions: -rw-r--r--

6818524: G1: use ergonomic resizing of PLABs
Summary: Employ PLABStats instances to record information about survivor and old PLABs, and use the recorded stats to adjust the sizes of survivor and old PLABS.
Reviewed-by: johnc, ysr
Contributed-by: Brandon Mitchell <brandon@twitter.com>

 /*
  * Copyright (c) 2001, 2012, 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_PARNEW_PARGCALLOCBUFFER_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP
 #include "memory/allocation.hpp"
 #include "memory/blockOffsetTable.hpp"
 #include "memory/threadLocalAllocBuffer.hpp"
 #include "utilities/globalDefinitions.hpp"
 // Forward decl.
 class PLABStats;
 // A per-thread allocation buffer used during GC.
 class ParGCAllocBuffer: public CHeapObj<mtGC> {
 protected:
   char head[32];
   size_t _word_sz;          // in HeapWord units
   HeapWord* _bottom;
   HeapWord* _top;
   HeapWord* _end;       // last allocatable address + 1
   HeapWord* _hard_end;  // _end + AlignmentReserve
   bool      _retained;  // whether we hold a _retained_filler
   MemRegion _retained_filler;
   // In support of ergonomic sizing of PLAB's
   size_t    _allocated;     // in HeapWord units
   size_t    _wasted;        // in HeapWord units
   char tail[32];
   static size_t FillerHeaderSize;
   static size_t AlignmentReserve;
 public:
   // Initializes the buffer to be empty, but with the given "word_sz".
   // Must get initialized with "set_buf" for an allocation to succeed.
   ParGCAllocBuffer(size_t word_sz);
   static const size_t min_size() {
     return ThreadLocalAllocBuffer::min_size();
   }
   static const size_t max_size() {
     return ThreadLocalAllocBuffer::max_size();
   }
   // If an allocation of the given "word_sz" can be satisfied within the
   // buffer, do the allocation, returning a pointer to the start of the
   // allocated block.  If the allocation request cannot be satisfied,
   // return NULL.
   HeapWord* allocate(size_t word_sz) {
     HeapWord* res = _top;
     if (pointer_delta(_end, _top) >= word_sz) {
       _top = _top + word_sz;
       return res;
     } else {
       return NULL;
     }
   }
   // Undo the last allocation in the buffer, which is required to be of the
   // "obj" of the given "word_sz".
   void undo_allocation(HeapWord* obj, size_t word_sz) {
     assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
     assert(pointer_delta(_top, obj)     == word_sz, "Bad undo");
     _top = obj;
   }
   // The total (word) size of the buffer, including both allocated and
   // unallocted space.
   size_t word_sz() { return _word_sz; }
   // Should only be done if we are about to reset with a new buffer of the
   // given size.
   void set_word_size(size_t new_word_sz) {
     assert(new_word_sz > AlignmentReserve, "Too small");
     _word_sz = new_word_sz;
   }
   // The number of words of unallocated space remaining in the buffer.
   size_t words_remaining() {
     assert(_end >= _top, "Negative buffer");
     return pointer_delta(_end, _top, HeapWordSize);
   }
   bool contains(void* addr) {
     return (void*)_bottom <= addr && addr < (void*)_hard_end;
   }
   // Sets the space of the buffer to be [buf, space+word_sz()).
   void set_buf(HeapWord* buf) {
     _bottom   = buf;
     _top      = _bottom;
     _hard_end = _bottom + word_sz();
     _end      = _hard_end - AlignmentReserve;
     assert(_end >= _top, "Negative buffer");
     // In support of ergonomic sizing
     _allocated += word_sz();
   }
   // Flush the stats supporting ergonomic sizing of PLAB's
   void flush_stats(PLABStats* stats);
   void flush_stats_and_retire(PLABStats* stats, bool end_of_gc, bool retain) {
     // We flush the stats first in order to get a reading of
     // unused space in the last buffer.
     if (ResizePLAB) {
       flush_stats(stats);
     }
     // Retire the last allocation buffer.
     retire(end_of_gc, retain);
   }
   // Force future allocations to fail and queries for contains()
   // to return false
   void invalidate() {
     assert(!_retained, "Shouldn't retain an invalidated buffer.");
     _end    = _hard_end;
     _wasted += pointer_delta(_end, _top);  // unused  space
     _top    = _end;      // force future allocations to fail
     _bottom = _end;      // force future contains() queries to return false
   }
   // Fills in the unallocated portion of the buffer with a garbage object.
   // If "end_of_gc" is TRUE, is after the last use in the GC.  IF "retain"
   // is true, attempt to re-use the unused portion in the next GC.
   void retire(bool end_of_gc, bool retain);
   void print() PRODUCT_RETURN;
 };
 // PLAB stats book-keeping
 class PLABStats VALUE_OBJ_CLASS_SPEC {
   size_t _allocated;      // total allocated
   size_t _wasted;         // of which wasted (internal fragmentation)
   size_t _unused;         // Unused in last buffer
   size_t _used;           // derived = allocated - wasted - unused
   size_t _desired_plab_sz;// output of filter (below), suitably trimmed and quantized
   AdaptiveWeightedAverage
          _filter;         // integrator with decay
  public:
   PLABStats(size_t desired_plab_sz_, unsigned wt) :
     _allocated(0),
     _wasted(0),
     _unused(0),
     _used(0),
     _desired_plab_sz(desired_plab_sz_),
     _filter(wt)
   {
     size_t min_sz = min_size();
     size_t max_sz = max_size();
     size_t aligned_min_sz = align_object_size(min_sz);
     size_t aligned_max_sz = align_object_size(max_sz);
     assert(min_sz <= aligned_min_sz && max_sz >= aligned_max_sz &&
            min_sz <= max_sz,
            "PLAB clipping computation in adjust_desired_plab_sz()"
            " may be incorrect");
   }
   static const size_t min_size() {
     return ParGCAllocBuffer::min_size();
   }
   static const size_t max_size() {
     return ParGCAllocBuffer::max_size();
   }
   size_t desired_plab_sz() {
     return _desired_plab_sz;
   }
   void adjust_desired_plab_sz(); // filter computation, latches output to
                                  // _desired_plab_sz, clears sensor accumulators
   void add_allocated(size_t v) {
     Atomic::add_ptr(v, &_allocated);
   }
   void add_unused(size_t v) {
     Atomic::add_ptr(v, &_unused);
   }
   void add_wasted(size_t v) {
     Atomic::add_ptr(v, &_wasted);
   }
 };
 class ParGCAllocBufferWithBOT: public ParGCAllocBuffer {
   BlockOffsetArrayContigSpace _bt;
   BlockOffsetSharedArray*     _bsa;
   HeapWord*                   _true_end;  // end of the whole ParGCAllocBuffer
   static const size_t ChunkSizeInWords;
   static const size_t ChunkSizeInBytes;
   HeapWord* allocate_slow(size_t word_sz);
   void fill_region_with_block(MemRegion mr, bool contig);
 public:
   ParGCAllocBufferWithBOT(size_t word_sz, BlockOffsetSharedArray* bsa);
   HeapWord* allocate(size_t word_sz) {
     HeapWord* res = ParGCAllocBuffer::allocate(word_sz);
     if (res != NULL) {
       _bt.alloc_block(res, word_sz);
     } else {
       res = allocate_slow(word_sz);
     }
     return res;
   }
   void undo_allocation(HeapWord* obj, size_t word_sz);
   void set_buf(HeapWord* buf_start) {
     ParGCAllocBuffer::set_buf(buf_start);
     _true_end = _hard_end;
     _bt.set_region(MemRegion(buf_start, word_sz()));
     _bt.initialize_threshold();
   }
   void retire(bool end_of_gc, bool retain);
   MemRegion range() {
     return MemRegion(_top, _true_end);
   }
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/shared/parGCAllocBuffer.hpp@aaf61e68b255 (annotated)

src/share/vm/gc_implementation/shared/parGCAllocBuffer.hpp