1 /* |
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2 * Copyright (c) 2002, 2008, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. |
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8 * |
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9 * This code is distributed in the hope that it will be useful, but WITHOUT |
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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12 * version 2 for more details (a copy is included in the LICENSE file that |
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13 * accompanied this code). |
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14 * |
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15 * You should have received a copy of the GNU General Public License version |
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16 * 2 along with this work; if not, write to the Free Software Foundation, |
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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18 * |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 // |
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26 // PrefetchQueue is a FIFO queue of variable length (currently 8). |
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27 // |
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28 // We need to examine the performance penalty of variable lengths. |
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29 // We may also want to split this into cpu dependent bits. |
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30 // |
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31 |
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32 const int PREFETCH_QUEUE_SIZE = 8; |
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33 |
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34 class PrefetchQueue : public CHeapObj { |
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35 private: |
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36 void* _prefetch_queue[PREFETCH_QUEUE_SIZE]; |
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37 uint _prefetch_index; |
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38 |
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39 public: |
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40 int length() { return PREFETCH_QUEUE_SIZE; } |
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41 |
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42 inline void clear() { |
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43 for(int i=0; i<PREFETCH_QUEUE_SIZE; i++) { |
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44 _prefetch_queue[i] = NULL; |
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45 } |
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46 _prefetch_index = 0; |
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47 } |
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48 |
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49 template <class T> inline void* push_and_pop(T* p) { |
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50 oop o = oopDesc::load_decode_heap_oop_not_null(p); |
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51 Prefetch::write(o->mark_addr(), 0); |
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52 // This prefetch is intended to make sure the size field of array |
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53 // oops is in cache. It assumes the the object layout is |
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54 // mark -> klass -> size, and that mark and klass are heapword |
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55 // sized. If this should change, this prefetch will need updating! |
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56 Prefetch::write(o->mark_addr() + (HeapWordSize*2), 0); |
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57 _prefetch_queue[_prefetch_index++] = p; |
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58 _prefetch_index &= (PREFETCH_QUEUE_SIZE-1); |
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59 return _prefetch_queue[_prefetch_index]; |
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60 } |
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61 |
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62 // Stores a NULL pointer in the pop'd location. |
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63 inline void* pop() { |
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64 _prefetch_queue[_prefetch_index++] = NULL; |
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65 _prefetch_index &= (PREFETCH_QUEUE_SIZE-1); |
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66 return _prefetch_queue[_prefetch_index]; |
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67 } |
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68 }; |
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