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40 * Authors: Erik Hallnor
45 * Declaration of a structure to manage MSHRs.
48 #ifndef __MEM_CACHE_MSHR_QUEUE_HH__
49 #define __MEM_CACHE_MSHR_QUEUE_HH__
53 #include "mem/cache/mshr.hh"
54 #include "mem/packet.hh"
55 #include "sim/drain.hh"
58 * A Class for maintaining a list of pending and allocated memory requests.
60 class MSHRQueue : public Drainable
63 /** Local label (for functional print requests) */
64 const std::string label;
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.
75 * The number of entries to hold in reserve. This is needed because copy
76 * operations can allocate upto 4 entries at one time.
81 * The number of entries to reserve for future demand accesses.
82 * Prevent prefetcher from taking all mshr entries
84 const int demandReserve;
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. */
92 /** Holds non allocated entries. */
95 MSHR::Iterator addToReadyList(MSHR *mshr);
99 /** The number of allocated entries. */
101 /** The number of entries that have been forwarded to the bus. */
102 int inServiceEntries;
103 /** The index of this queue within the cache (MSHR queue vs. write
108 * Create a queue with a given number of entries.
109 * @param num_entrys The number of entries in this queue.
110 * @param reserve The minimum number of entries needed to satisfy
112 * @param demand_reserve The minimum number of entries needed to satisfy
115 MSHRQueue(const std::string &_label, int num_entries, int reserve,
116 int demand_reserve, int index);
119 * Find the first MSHR that matches the provided address.
120 * @param blk_addr The block address to find.
121 * @param is_secure True if the target memory space is secure.
122 * @return Pointer to the matching MSHR, null if not found.
124 MSHR *findMatch(Addr blk_addr, bool is_secure) const;
127 * Find and return all the matching entries in the provided vector.
128 * @param blk_addr The block address to find.
129 * @param is_secure True if the target memory space is secure.
130 * @param matches The vector to return pointers to the matching entries.
131 * @return True if any matches are found, false otherwise.
133 bool findMatches(Addr blk_addr, bool is_secure,
134 std::vector<MSHR*>& matches) const;
137 * Find any pending requests that overlap the given request.
138 * @param blk_addr Block address.
139 * @param is_secure True if the target memory space is secure.
140 * @return A pointer to the earliest matching MSHR.
142 MSHR *findPending(Addr blk_addr, bool is_secure) const;
144 bool checkFunctional(PacketPtr pkt, Addr blk_addr);
147 * Allocates a new MSHR for the request and size. This places the request
148 * as the first target in the MSHR.
150 * @param blk_addr The address of the block.
151 * @param blk_size The number of bytes to request.
152 * @param pkt The original miss.
153 * @param when_ready When should the MSHR be ready to act upon.
154 * @param order The logical order of this MSHR
155 * @param alloc_on_fill Should the cache allocate a block on fill
157 * @return The a pointer to the MSHR allocated.
159 * @pre There are free entries.
161 MSHR *allocate(Addr blk_addr, unsigned blk_size, PacketPtr pkt,
162 Tick when_ready, Counter order, bool alloc_on_fill);
165 * Removes the given MSHR from the queue. This places the MSHR on the
169 void deallocate(MSHR *mshr);
172 * Remove a MSHR from the queue. Returns an iterator into the
174 * @param mshr The MSHR to remove.
175 * @return An iterator to the next entry in the allocatedList.
177 MSHR::Iterator deallocateOne(MSHR *mshr);
180 * Moves the MSHR to the front of the pending list if it is not
182 * @param mshr The entry to move.
184 void moveToFront(MSHR *mshr);
187 * Mark the given MSHR as in service. This removes the MSHR from the
188 * readyList or deallocates the MSHR if it does not expect a response.
190 * @param mshr The MSHR to mark in service.
191 * @param pending_dirty_resp Whether we expect a dirty response
194 void markInService(MSHR *mshr, bool pending_dirty_resp);
197 * Mark an in service entry as pending, used to resend a request.
198 * @param mshr The MSHR to resend.
200 void markPending(MSHR *mshr);
203 * Deallocate top target, possibly freeing the MSHR
204 * @return if MSHR queue is no longer full
206 bool forceDeallocateTarget(MSHR *mshr);
209 * Returns true if the pending list is not empty.
210 * @return True if there are outstanding requests.
212 bool havePending() const
214 return !readyList.empty();
218 * Returns true if there are no free entries.
219 * @return True if this queue is full.
223 return (allocated > numEntries - numReserve);
227 * Returns true if sufficient mshrs for prefetch.
228 * @return True if sufficient mshrs for prefetch.
230 bool canPrefetch() const
232 return (allocated < numEntries - (numReserve + demandReserve));
236 * Returns the MSHR at the head of the readyList.
237 * @return The next request to service.
239 MSHR *getNextMSHR() const
241 if (readyList.empty() || readyList.front()->readyTime > curTick()) {
244 return readyList.front();
247 Tick nextMSHRReadyTime() const
249 return readyList.empty() ? MaxTick : readyList.front()->readyTime;
252 DrainState drain() override;
255 #endif //__MEM_CACHE_MSHR_QUEUE_HH__