Mercurial > hg > truffle
diff src/share/vm/gc_implementation/parallelScavenge/prefetchQueue.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ba764ed4b6f2 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/parallelScavenge/prefetchQueue.hpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,67 @@ +/* + * Copyright 2002-2003 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 dependant bits. +// + +const int PREFETCH_QUEUE_SIZE = 8; + +class PrefetchQueue : public CHeapObj { + private: + oop* _prefetch_queue[PREFETCH_QUEUE_SIZE]; + unsigned int _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; + } + + inline oop* push_and_pop(oop* p) { + Prefetch::write((*p)->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((*p)->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 oop* pop() { + _prefetch_queue[_prefetch_index++] = NULL; + _prefetch_index &= (PREFETCH_QUEUE_SIZE-1); + return _prefetch_queue[_prefetch_index]; + } +};