Mercurial > hg > truffle
view src/share/vm/gc_implementation/parallelScavenge/prefetchQueue.hpp @ 642:660978a2a31a
6791178: Specialize for zero as the compressed oop vm heap base
Summary: Use zero based compressed oops if java heap is below 32gb and unscaled compressed oops if java heap is below 4gb.
Reviewed-by: never, twisti, jcoomes, coleenp
author | kvn |
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date | Thu, 12 Mar 2009 10:37:46 -0700 |
parents | 98cb887364d3 |
children | c18cbe5936b8 |
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/* * Copyright 2002-2008 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. * */ // // PrefetchQueue is a FIFO queue of variable length (currently 8). // // We need to examine the performance penalty of variable lengths. // We may also want to split this into cpu dependent bits. // const int PREFETCH_QUEUE_SIZE = 8; class PrefetchQueue : public CHeapObj { private: void* _prefetch_queue[PREFETCH_QUEUE_SIZE]; uint _prefetch_index; public: int length() { return PREFETCH_QUEUE_SIZE; } inline void clear() { for(int i=0; i<PREFETCH_QUEUE_SIZE; i++) { _prefetch_queue[i] = NULL; } _prefetch_index = 0; } template <class T> inline void* push_and_pop(T* p) { oop o = oopDesc::load_decode_heap_oop_not_null(p); Prefetch::write(o->mark_addr(), 0); // This prefetch is intended to make sure the size field of array // oops is in cache. It assumes the the object layout is // mark -> klass -> size, and that mark and klass are heapword // sized. If this should change, this prefetch will need updating! Prefetch::write(o->mark_addr() + (HeapWordSize*2), 0); _prefetch_queue[_prefetch_index++] = p; _prefetch_index &= (PREFETCH_QUEUE_SIZE-1); return _prefetch_queue[_prefetch_index]; } // Stores a NULL pointer in the pop'd location. inline void* pop() { _prefetch_queue[_prefetch_index++] = NULL; _prefetch_index &= (PREFETCH_QUEUE_SIZE-1); return _prefetch_queue[_prefetch_index]; } };