mshr_queue.hh revision 10764:b32578b2af99
1/* 2 * Copyright (c) 2012-2013, 2015 ARM Limited 3 * All rights reserved. 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2003-2005 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Erik Hallnor 41 * Andreas Sandberg 42 */ 43 44/** @file 45 * Declaration of a structure to manage MSHRs. 46 */ 47 48#ifndef __MEM_CACHE_MSHR_QUEUE_HH__ 49#define __MEM_CACHE_MSHR_QUEUE_HH__ 50 51#include <vector> 52 53#include "mem/cache/mshr.hh" 54#include "mem/packet.hh" 55#include "sim/drain.hh" 56 57/** 58 * A Class for maintaining a list of pending and allocated memory requests. 59 */ 60class MSHRQueue : public Drainable 61{ 62 private: 63 /** Local label (for functional print requests) */ 64 const std::string label; 65 66 // Parameters 67 /** 68 * The total number of entries in this queue. This number is set as the 69 * number of entries requested plus (numReserve - 1). This allows for 70 * the same number of effective entries while still maintaining the reserve. 71 */ 72 const int numEntries; 73 74 /** 75 * The number of entries to hold in reserve. This is needed because copy 76 * operations can allocate upto 4 entries at one time. 77 */ 78 const int numReserve; 79 80 /** 81 * The number of entries to reserve for future demand accesses. 82 * Prevent prefetcher from taking all mshr entries 83 */ 84 const int demandReserve; 85 86 /** MSHR storage. */ 87 std::vector<MSHR> registers; 88 /** Holds pointers to all allocated entries. */ 89 MSHR::List allocatedList; 90 /** Holds pointers to entries that haven't been sent to the bus. */ 91 MSHR::List readyList; 92 /** Holds non allocated entries. */ 93 MSHR::List freeList; 94 95 /** Drain manager to inform of a completed drain */ 96 DrainManager *drainManager; 97 98 MSHR::Iterator addToReadyList(MSHR *mshr); 99 100 101 public: 102 /** The number of allocated entries. */ 103 int allocated; 104 /** The number of entries that have been forwarded to the bus. */ 105 int inServiceEntries; 106 /** The index of this queue within the cache (MSHR queue vs. write 107 * buffer). */ 108 const int index; 109 110 /** 111 * Create a queue with a given number of entries. 112 * @param num_entrys The number of entries in this queue. 113 * @param reserve The minimum number of entries needed to satisfy 114 * any access. 115 * @param demand_reserve The minimum number of entries needed to satisfy 116 * demand accesses. 117 */ 118 MSHRQueue(const std::string &_label, int num_entries, int reserve, 119 int demand_reserve, int index); 120 121 /** 122 * Find the first MSHR that matches the provided address. 123 * @param blk_addr The block address to find. 124 * @param is_secure True if the target memory space is secure. 125 * @return Pointer to the matching MSHR, null if not found. 126 */ 127 MSHR *findMatch(Addr blk_addr, bool is_secure) const; 128 129 /** 130 * Find and return all the matching entries in the provided vector. 131 * @param blk_addr The block address to find. 132 * @param is_secure True if the target memory space is secure. 133 * @param matches The vector to return pointers to the matching entries. 134 * @return True if any matches are found, false otherwise. 135 */ 136 bool findMatches(Addr blk_addr, bool is_secure, 137 std::vector<MSHR*>& matches) const; 138 139 /** 140 * Find any pending requests that overlap the given request. 141 * @param blk_addr Block address. 142 * @param is_secure True if the target memory space is secure. 143 * @return A pointer to the earliest matching MSHR. 144 */ 145 MSHR *findPending(Addr blk_addr, bool is_secure) const; 146 147 bool checkFunctional(PacketPtr pkt, Addr blk_addr); 148 149 /** 150 * Allocates a new MSHR for the request and size. This places the request 151 * as the first target in the MSHR. 152 * 153 * @param blk_addr The address of the block. 154 * @param blk_size The number of bytes to request. 155 * @param pkt The original miss. 156 * @param when_ready When should the MSHR be ready to act upon. 157 * @param order The logical order of this MSHR 158 * 159 * @return The a pointer to the MSHR allocated. 160 * 161 * @pre There are free entries. 162 */ 163 MSHR *allocate(Addr blk_addr, unsigned blk_size, PacketPtr pkt, 164 Tick when_ready, Counter order); 165 166 /** 167 * Removes the given MSHR from the queue. This places the MSHR on the 168 * free list. 169 * @param mshr 170 */ 171 void deallocate(MSHR *mshr); 172 173 /** 174 * Remove a MSHR from the queue. Returns an iterator into the 175 * allocatedList for faster squash implementation. 176 * @param mshr The MSHR to remove. 177 * @return An iterator to the next entry in the allocatedList. 178 */ 179 MSHR::Iterator deallocateOne(MSHR *mshr); 180 181 /** 182 * Moves the MSHR to the front of the pending list if it is not 183 * in service. 184 * @param mshr The entry to move. 185 */ 186 void moveToFront(MSHR *mshr); 187 188 /** 189 * Mark the given MSHR as in service. This removes the MSHR from the 190 * readyList or deallocates the MSHR if it does not expect a response. 191 * 192 * @param mshr The MSHR to mark in service. 193 * @param pending_dirty_resp Whether we expect a dirty response 194 * from another cache 195 */ 196 void markInService(MSHR *mshr, bool pending_dirty_resp); 197 198 /** 199 * Mark an in service entry as pending, used to resend a request. 200 * @param mshr The MSHR to resend. 201 */ 202 void markPending(MSHR *mshr); 203 204 /** 205 * Squash outstanding requests with the given thread number. If a request 206 * is in service, just squashes the targets. 207 * @param threadNum The thread to squash. 208 */ 209 void squash(int threadNum); 210 211 /** 212 * Deallocate top target, possibly freeing the MSHR 213 * @return if MSHR queue is no longer full 214 */ 215 bool forceDeallocateTarget(MSHR *mshr); 216 217 /** 218 * Returns true if the pending list is not empty. 219 * @return True if there are outstanding requests. 220 */ 221 bool havePending() const 222 { 223 return !readyList.empty(); 224 } 225 226 /** 227 * Returns true if there are no free entries. 228 * @return True if this queue is full. 229 */ 230 bool isFull() const 231 { 232 return (allocated > numEntries - numReserve); 233 } 234 235 /** 236 * Returns true if sufficient mshrs for prefetch. 237 * @return True if sufficient mshrs for prefetch. 238 */ 239 bool canPrefetch() const 240 { 241 return (allocated < numEntries - (numReserve + demandReserve)); 242 } 243 244 /** 245 * Returns the MSHR at the head of the readyList. 246 * @return The next request to service. 247 */ 248 MSHR *getNextMSHR() const 249 { 250 if (readyList.empty() || readyList.front()->readyTime > curTick()) { 251 return NULL; 252 } 253 return readyList.front(); 254 } 255 256 Tick nextMSHRReadyTime() const 257 { 258 return readyList.empty() ? MaxTick : readyList.front()->readyTime; 259 } 260 261 unsigned int drain(DrainManager *dm); 262}; 263 264#endif //__MEM_CACHE_MSHR_QUEUE_HH__ 265