1 #ifdef USE_PRAGMA_IDENT_HDR 2 #pragma ident "@(#)prefetchQueue.hpp 1.13 07/05/05 17:05:28 JVM" 3 #endif 4 /* 5 * Copyright 2002-2003 Sun Microsystems, Inc. All Rights Reserved. 6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 7 * 8 * This code is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License version 2 only, as 10 * published by the Free Software Foundation. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 23 * CA 95054 USA or visit www.sun.com if you need additional information or 24 * have any questions. 25 * 26 */ 27 28 // 29 // PrefetchQueue is a FIFO queue of variable length (currently 8). 30 // 31 // We need to examine the performance penalty of variable lengths. 32 // We may also want to split this into cpu dependant bits. 33 // 34 35 const int PREFETCH_QUEUE_SIZE = 8; 36 37 class PrefetchQueue : public CHeapObj { 38 private: 39 oop* _prefetch_queue[PREFETCH_QUEUE_SIZE]; 40 unsigned int _prefetch_index; 41 42 public: 43 int length() { return PREFETCH_QUEUE_SIZE; } 44 45 inline void clear() { 46 for(int i=0; i<PREFETCH_QUEUE_SIZE; i++) { 47 _prefetch_queue[i] = NULL; 48 } 49 _prefetch_index = 0; 50 } 51 52 inline oop* push_and_pop(oop* p) { 53 Prefetch::write((*p)->mark_addr(), 0); 54 // This prefetch is intended to make sure the size field of array 55 // oops is in cache. It assumes the the object layout is 56 // mark -> klass -> size, and that mark and klass are heapword 57 // sized. If this should change, this prefetch will need updating! 58 Prefetch::write((*p)->mark_addr() + (HeapWordSize*2), 0); 59 _prefetch_queue[_prefetch_index++] = p; 60 _prefetch_index &= (PREFETCH_QUEUE_SIZE-1); 61 return _prefetch_queue[_prefetch_index]; 62 } 63 64 // Stores a NULL pointer in the pop'd location. 65 inline oop* pop() { 66 _prefetch_queue[_prefetch_index++] = NULL; 67 _prefetch_index &= (PREFETCH_QUEUE_SIZE-1); 68 return _prefetch_queue[_prefetch_index]; 69 } 70 }; 71 72 73