| /* |
| * 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 |
| * questions. |
| * |
| */ |
| |
| #ifndef SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP |
| #define SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP |
| #include "gc_interface/collectedHeap.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; |
| |
| // Flush the stats supporting ergonomic sizing of PLAB's |
| // Should not be called directly |
| void flush_stats(PLABStats* stats); |
| |
| 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); |
| virtual ~ParGCAllocBuffer() {} |
| |
| static const size_t min_size() { |
| // Make sure that we return something that is larger than AlignmentReserve |
| return align_object_size(MAX2(MinTLABSize / HeapWordSize, (uintx)oopDesc::header_size())) + AlignmentReserve; |
| } |
| |
| 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; |
| } |
| } |
| |
| // Allocate the object aligned to "alignment_in_bytes". |
| HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes); |
| |
| // 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()). |
| virtual 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 |
| // and retire the current buffer. |
| 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); |
| |
| // Since we have flushed the stats we need to clear |
| // the _allocated and _wasted fields. Not doing so |
| // will artifically inflate the values in the stats |
| // to which we add them. |
| // The next time we flush these values, we will add |
| // what we have just flushed in addition to the size |
| // of the buffers allocated between now and then. |
| _allocated = 0; |
| _wasted = 0; |
| } |
| // 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. |
| virtual 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) |
| { } |
| |
| 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(uint no_of_gc_workers); |
| // 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); |
| |
| virtual 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(); |
| } |
| |
| virtual void retire(bool end_of_gc, bool retain); |
| |
| MemRegion range() { |
| return MemRegion(_top, _true_end); |
| } |
| }; |
| |
| #endif // SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP |