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40 * Authors: Erik Hallnor
48 * Describes a cache based on template policies.
54 #include "base/misc.hh" // fatal, panic, and warn
55 #include "mem/cache/base.hh"
56 #include "mem/cache/blk.hh"
57 #include "mem/cache/mshr.hh"
58 #include "sim/eventq.hh"
64 * A template-policy based cache. The behavior of the cache can be altered by
65 * supplying different template policies. TagStore handles all tag and data
66 * storage @sa TagStore.
68 template <class TagStore>
69 class Cache : public BaseCache
72 /** Define the type of cache block to use. */
73 typedef typename TagStore::BlkType BlkType;
74 /** A typedef for a list of BlkType pointers. */
75 typedef typename TagStore::BlkList BlkList;
79 class CpuSidePort : public CachePort
82 CpuSidePort(const std::string &_name,
83 Cache<TagStore> *_cache,
84 const std::string &_label);
86 // BaseCache::CachePort just has a BaseCache *; this function
87 // lets us get back the type info we lost when we stored the
88 // cache pointer there.
89 Cache<TagStore> *myCache() {
90 return static_cast<Cache<TagStore> *>(cache);
93 virtual void getDeviceAddressRanges(AddrRangeList &resp,
96 virtual bool recvTiming(PacketPtr pkt);
98 virtual Tick recvAtomic(PacketPtr pkt);
100 virtual void recvFunctional(PacketPtr pkt);
103 class MemSidePort : public CachePort
106 MemSidePort(const std::string &_name,
107 Cache<TagStore> *_cache,
108 const std::string &_label);
110 // BaseCache::CachePort just has a BaseCache *; this function
111 // lets us get back the type info we lost when we stored the
112 // cache pointer there.
113 Cache<TagStore> *myCache() {
114 return static_cast<Cache<TagStore> *>(cache);
119 void processSendEvent();
121 virtual void getDeviceAddressRanges(AddrRangeList &resp,
124 virtual bool recvTiming(PacketPtr pkt);
126 virtual void recvRetry();
128 virtual Tick recvAtomic(PacketPtr pkt);
130 virtual void recvFunctional(PacketPtr pkt);
132 typedef EventWrapper<MemSidePort, &MemSidePort::processSendEvent>
136 /** Tag and data Storage */
140 BasePrefetcher *prefetcher;
142 /** Temporary cache block for occasional transitory use */
146 * This cache should allocate a block on a line-sized write miss.
148 const bool doFastWrites;
151 * Notify the prefetcher on every access, not just misses.
153 const bool prefetchOnAccess;
156 * Does all the processing necessary to perform the provided request.
157 * @param pkt The memory request to perform.
158 * @param lat The latency of the access.
159 * @param writebacks List for any writebacks that need to be performed.
160 * @param update True if the replacement data should be updated.
161 * @return Boolean indicating whether the request was satisfied.
163 bool access(PacketPtr pkt, BlkType *&blk,
164 int &lat, PacketList &writebacks);
167 *Handle doing the Compare and Swap function for SPARC.
169 void cmpAndSwap(BlkType *blk, PacketPtr pkt);
172 * Find a block frame for new block at address addr, assuming that
173 * the block is not currently in the cache. Append writebacks if
174 * any to provided packet list. Return free block frame. May
175 * return NULL if there are no replaceable blocks at the moment.
177 BlkType *allocateBlock(Addr addr, PacketList &writebacks);
180 * Populates a cache block and handles all outstanding requests for the
181 * satisfied fill request. This version takes two memory requests. One
182 * contains the fill data, the other is an optional target to satisfy.
183 * @param pkt The memory request with the fill data.
184 * @param blk The cache block if it already exists.
185 * @param writebacks List for any writebacks that need to be performed.
186 * @return Pointer to the new cache block.
188 BlkType *handleFill(PacketPtr pkt, BlkType *blk,
189 PacketList &writebacks);
191 void satisfyCpuSideRequest(PacketPtr pkt, BlkType *blk,
192 bool deferred_response = false,
193 bool pending_downgrade = false);
194 bool satisfyMSHR(MSHR *mshr, PacketPtr pkt, BlkType *blk);
196 void doTimingSupplyResponse(PacketPtr req_pkt, uint8_t *blk_data,
197 bool already_copied, bool pending_inval);
200 * Sets the blk to the new state.
201 * @param blk The cache block being snooped.
202 * @param new_state The new coherence state for the block.
204 void handleSnoop(PacketPtr ptk, BlkType *blk,
205 bool is_timing, bool is_deferred, bool pending_inval);
208 * Create a writeback request for the given block.
209 * @param blk The block to writeback.
210 * @return The writeback request for the block.
212 PacketPtr writebackBlk(BlkType *blk);
215 /** Instantiates a basic cache object. */
216 Cache(const Params *p, TagStore *tags, BasePrefetcher *prefetcher);
218 virtual Port *getPort(const std::string &if_name, int idx = -1);
223 * Performs the access specified by the request.
224 * @param pkt The request to perform.
225 * @return The result of the access.
227 bool timingAccess(PacketPtr pkt);
230 * Performs the access specified by the request.
231 * @param pkt The request to perform.
232 * @return The result of the access.
234 Tick atomicAccess(PacketPtr pkt);
237 * Performs the access specified by the request.
238 * @param pkt The request to perform.
239 * @param fromCpuSide from the CPU side port or the memory side port
241 void functionalAccess(PacketPtr pkt, bool fromCpuSide);
244 * Handles a response (cache line fill/write ack) from the bus.
245 * @param pkt The request being responded to.
247 void handleResponse(PacketPtr pkt);
250 * Snoops bus transactions to maintain coherence.
251 * @param pkt The current bus transaction.
253 void snoopTiming(PacketPtr pkt);
256 * Snoop for the provided request in the cache and return the estimated
257 * time of completion.
258 * @param pkt The memory request to snoop
259 * @return The estimated completion time.
261 Tick snoopAtomic(PacketPtr pkt);
264 * Squash all requests associated with specified thread.
265 * intended for use by I-cache.
266 * @param threadNum The thread to squash.
268 void squash(int threadNum);
271 * Generate an appropriate downstream bus request packet for the
273 * @param cpu_pkt The upstream request that needs to be satisfied.
274 * @param blk The block currently in the cache corresponding to
275 * cpu_pkt (NULL if none).
276 * @param needsExclusive Indicates that an exclusive copy is required
277 * even if the request in cpu_pkt doesn't indicate that.
278 * @return A new Packet containing the request, or NULL if the
279 * current request in cpu_pkt should just be forwarded on.
281 PacketPtr getBusPacket(PacketPtr cpu_pkt, BlkType *blk,
282 bool needsExclusive);
285 * Return the next MSHR to service, either a pending miss from the
286 * mshrQueue, a buffered write from the write buffer, or something
287 * from the prefetcher. This function is responsible for
288 * prioritizing among those sources on the fly.
293 * Selects an outstanding request to service. Called when the
294 * cache gets granted the downstream bus in timing mode.
295 * @return The request to service, NULL if none found.
297 PacketPtr getTimingPacket();
300 * Marks a request as in service (sent on the bus). This can have side
301 * effect since storage for no response commands is deallocated once they
302 * are successfully sent.
303 * @param pkt The request that was sent on the bus.
305 void markInService(MSHR *mshr, PacketPtr pkt = 0);
308 * Perform the given writeback request.
309 * @param pkt The writeback request.
311 void doWriteback(PacketPtr pkt);
314 * Return whether there are any outstanding misses.
316 bool outstandingMisses() const
318 return mshrQueue.allocated != 0;
321 CacheBlk *findBlock(Addr addr) {
322 return tags->findBlock(addr);
325 bool inCache(Addr addr) {
326 return (tags->findBlock(addr) != 0);
329 bool inMissQueue(Addr addr) {
330 return (mshrQueue.findMatch(addr) != 0);
334 * Find next request ready time from among possible sources.
336 Tick nextMSHRReadyTime();
339 #endif // __CACHE_HH__