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40 * Authors: Erik Hallnor
47 * Declares a basic cache interface BaseCache.
50 #ifndef __MEM_CACHE_BASE_HH__
51 #define __MEM_CACHE_BASE_HH__
58 #include "base/misc.hh"
59 #include "base/statistics.hh"
60 #include "base/trace.hh"
61 #include "base/types.hh"
62 #include "debug/Cache.hh"
63 #include "debug/CachePort.hh"
64 #include "mem/cache/mshr_queue.hh"
65 #include "mem/mem_object.hh"
66 #include "mem/packet.hh"
67 #include "mem/qport.hh"
68 #include "mem/request.hh"
69 #include "params/BaseCache.hh"
70 #include "sim/eventq.hh"
71 #include "sim/full_system.hh"
72 #include "sim/sim_exit.hh"
73 #include "sim/system.hh"
77 * A basic cache interface. Implements some common functions for speed.
79 class BaseCache : public MemObject
82 * Indexes to enumerate the MSHR queues.
91 * Reasons for caches to be blocked.
94 Blocked_NoMSHRs = MSHRQueue_MSHRs,
95 Blocked_NoWBBuffers = MSHRQueue_WriteBuffer,
103 * A cache master port is used for the memory-side port of the
104 * cache, and in addition to the basic timing port that only sends
105 * response packets through a transmit list, it also offers the
106 * ability to schedule and send request packets (requests &
107 * writebacks). The send event is scheduled through schedSendEvent,
108 * and the sendDeferredPacket of the timing port is modified to
109 * consider both the transmit list and the requests from the MSHR.
111 class CacheMasterPort : public QueuedMasterPort
117 * Schedule a send of a request packet (from the MSHR). Note
118 * that we could already have a retry outstanding.
120 void schedSendEvent(Tick time)
122 DPRINTF(CachePort, "Scheduling send event at %llu\n", time);
123 reqQueue.schedSendEvent(time);
128 CacheMasterPort(const std::string &_name, BaseCache *_cache,
129 ReqPacketQueue &_reqQueue,
130 SnoopRespPacketQueue &_snoopRespQueue) :
131 QueuedMasterPort(_name, _cache, _reqQueue, _snoopRespQueue)
135 * Memory-side port always snoops.
137 * @return always true
139 virtual bool isSnooping() const { return true; }
143 * A cache slave port is used for the CPU-side port of the cache,
144 * and it is basically a simple timing port that uses a transmit
145 * list for responses to the CPU (or connected master). In
146 * addition, it has the functionality to block the port for
147 * incoming requests. If blocked, the port will issue a retry once
150 class CacheSlavePort : public QueuedSlavePort
155 /** Do not accept any new requests. */
158 /** Return to normal operation and accept new requests. */
161 bool isBlocked() const { return blocked; }
165 CacheSlavePort(const std::string &_name, BaseCache *_cache,
166 const std::string &_label);
168 /** A normal packet queue used to store responses. */
169 RespPacketQueue queue;
177 void processSendRetry();
179 EventWrapper<CacheSlavePort,
180 &CacheSlavePort::processSendRetry> sendRetryEvent;
184 CacheSlavePort *cpuSidePort;
185 CacheMasterPort *memSidePort;
189 /** Miss status registers */
192 /** Write/writeback buffer */
193 MSHRQueue writeBuffer;
196 * Allocate a buffer, passing the time indicating when schedule an
197 * event to the queued port to go and ask the MSHR and write queue
198 * if they have packets to send.
200 * allocateBufferInternal() function is called in:
201 * - MSHR allocateWriteBuffer (unchached write forwarded to WriteBuffer);
202 * - MSHR allocateMissBuffer (miss in MSHR queue);
204 MSHR *allocateBufferInternal(MSHRQueue *mq, Addr addr, int size,
205 PacketPtr pkt, Tick time,
208 // check that the address is block aligned since we rely on
209 // this in a number of places when checking for matches and
211 assert(addr == blockAlign(addr));
213 MSHR *mshr = mq->allocate(addr, size, pkt, time, order++,
214 allocOnFill(pkt->cmd));
217 setBlocked((BlockedCause)mq->index);
222 schedMemSideSendEvent(time);
227 void markInServiceInternal(MSHR *mshr, bool pending_modified_resp)
229 MSHRQueue *mq = mshr->queue;
230 bool wasFull = mq->isFull();
231 mq->markInService(mshr, pending_modified_resp);
232 if (wasFull && !mq->isFull()) {
233 clearBlocked((BlockedCause)mq->index);
238 * Determine if we should allocate on a fill or not.
240 * @param cmd Packet command being added as an MSHR target
242 * @return Whether we should allocate on a fill or not
244 virtual bool allocOnFill(MemCmd cmd) const = 0;
247 * Write back dirty blocks in the cache using functional accesses.
249 virtual void memWriteback() = 0;
251 * Invalidates all blocks in the cache.
253 * @warn Dirty cache lines will not be written back to
254 * memory. Make sure to call functionalWriteback() first if you
255 * want the to write them to memory.
257 virtual void memInvalidate() = 0;
259 * Determine if there are any dirty blocks in the cache.
261 * \return true if at least one block is dirty, false otherwise.
263 virtual bool isDirty() const = 0;
266 * Determine if an address is in the ranges covered by this
267 * cache. This is useful to filter snoops.
269 * @param addr Address to check against
271 * @return If the address in question is in range
273 bool inRange(Addr addr) const;
275 /** Block size of this cache */
276 const unsigned blkSize;
279 * The latency of tag lookup of a cache. It occurs when there is
280 * an access to the cache.
282 const Cycles lookupLatency;
285 * This is the forward latency of the cache. It occurs when there
286 * is a cache miss and a request is forwarded downstream, in
287 * particular an outbound miss.
289 const Cycles forwardLatency;
291 /** The latency to fill a cache block */
292 const Cycles fillLatency;
295 * The latency of sending reponse to its upper level cache/core on
296 * a linefill. The responseLatency parameter captures this
299 const Cycles responseLatency;
301 /** The number of targets for each MSHR. */
304 /** Do we forward snoops from mem side port through to cpu side port? */
308 * Is this cache read only, for example the instruction cache, or
309 * table-walker cache. A cache that is read only should never see
310 * any writes, and should never get any dirty data (and hence
311 * never have to do any writebacks).
313 const bool isReadOnly;
316 * Bit vector of the blocking reasons for the access path.
321 /** Increasing order number assigned to each incoming request. */
324 /** Stores time the cache blocked for statistics. */
327 /** Pointer to the MSHR that has no targets. */
330 /** The number of misses to trigger an exit event. */
334 * The address range to which the cache responds on the CPU side.
335 * Normally this is all possible memory addresses. */
336 const AddrRangeList addrRanges;
339 /** System we are currently operating in. */
344 * @addtogroup CacheStatistics
348 /** Number of hits per thread for each type of command. @sa Packet::Command */
349 Stats::Vector hits[MemCmd::NUM_MEM_CMDS];
350 /** Number of hits for demand accesses. */
351 Stats::Formula demandHits;
352 /** Number of hit for all accesses. */
353 Stats::Formula overallHits;
355 /** Number of misses per thread for each type of command. @sa Packet::Command */
356 Stats::Vector misses[MemCmd::NUM_MEM_CMDS];
357 /** Number of misses for demand accesses. */
358 Stats::Formula demandMisses;
359 /** Number of misses for all accesses. */
360 Stats::Formula overallMisses;
363 * Total number of cycles per thread/command spent waiting for a miss.
364 * Used to calculate the average miss latency.
366 Stats::Vector missLatency[MemCmd::NUM_MEM_CMDS];
367 /** Total number of cycles spent waiting for demand misses. */
368 Stats::Formula demandMissLatency;
369 /** Total number of cycles spent waiting for all misses. */
370 Stats::Formula overallMissLatency;
372 /** The number of accesses per command and thread. */
373 Stats::Formula accesses[MemCmd::NUM_MEM_CMDS];
374 /** The number of demand accesses. */
375 Stats::Formula demandAccesses;
376 /** The number of overall accesses. */
377 Stats::Formula overallAccesses;
379 /** The miss rate per command and thread. */
380 Stats::Formula missRate[MemCmd::NUM_MEM_CMDS];
381 /** The miss rate of all demand accesses. */
382 Stats::Formula demandMissRate;
383 /** The miss rate for all accesses. */
384 Stats::Formula overallMissRate;
386 /** The average miss latency per command and thread. */
387 Stats::Formula avgMissLatency[MemCmd::NUM_MEM_CMDS];
388 /** The average miss latency for demand misses. */
389 Stats::Formula demandAvgMissLatency;
390 /** The average miss latency for all misses. */
391 Stats::Formula overallAvgMissLatency;
393 /** The total number of cycles blocked for each blocked cause. */
394 Stats::Vector blocked_cycles;
395 /** The number of times this cache blocked for each blocked cause. */
396 Stats::Vector blocked_causes;
398 /** The average number of cycles blocked for each blocked cause. */
399 Stats::Formula avg_blocked;
401 /** The number of fast writes (WH64) performed. */
402 Stats::Scalar fastWrites;
404 /** The number of cache copies performed. */
405 Stats::Scalar cacheCopies;
407 /** Number of blocks written back per thread. */
408 Stats::Vector writebacks;
410 /** Number of misses that hit in the MSHRs per command and thread. */
411 Stats::Vector mshr_hits[MemCmd::NUM_MEM_CMDS];
412 /** Demand misses that hit in the MSHRs. */
413 Stats::Formula demandMshrHits;
414 /** Total number of misses that hit in the MSHRs. */
415 Stats::Formula overallMshrHits;
417 /** Number of misses that miss in the MSHRs, per command and thread. */
418 Stats::Vector mshr_misses[MemCmd::NUM_MEM_CMDS];
419 /** Demand misses that miss in the MSHRs. */
420 Stats::Formula demandMshrMisses;
421 /** Total number of misses that miss in the MSHRs. */
422 Stats::Formula overallMshrMisses;
424 /** Number of misses that miss in the MSHRs, per command and thread. */
425 Stats::Vector mshr_uncacheable[MemCmd::NUM_MEM_CMDS];
426 /** Total number of misses that miss in the MSHRs. */
427 Stats::Formula overallMshrUncacheable;
429 /** Total cycle latency of each MSHR miss, per command and thread. */
430 Stats::Vector mshr_miss_latency[MemCmd::NUM_MEM_CMDS];
431 /** Total cycle latency of demand MSHR misses. */
432 Stats::Formula demandMshrMissLatency;
433 /** Total cycle latency of overall MSHR misses. */
434 Stats::Formula overallMshrMissLatency;
436 /** Total cycle latency of each MSHR miss, per command and thread. */
437 Stats::Vector mshr_uncacheable_lat[MemCmd::NUM_MEM_CMDS];
438 /** Total cycle latency of overall MSHR misses. */
439 Stats::Formula overallMshrUncacheableLatency;
442 /** The total number of MSHR accesses per command and thread. */
443 Stats::Formula mshrAccesses[MemCmd::NUM_MEM_CMDS];
444 /** The total number of demand MSHR accesses. */
445 Stats::Formula demandMshrAccesses;
446 /** The total number of MSHR accesses. */
447 Stats::Formula overallMshrAccesses;
450 /** The miss rate in the MSHRs pre command and thread. */
451 Stats::Formula mshrMissRate[MemCmd::NUM_MEM_CMDS];
452 /** The demand miss rate in the MSHRs. */
453 Stats::Formula demandMshrMissRate;
454 /** The overall miss rate in the MSHRs. */
455 Stats::Formula overallMshrMissRate;
457 /** The average latency of an MSHR miss, per command and thread. */
458 Stats::Formula avgMshrMissLatency[MemCmd::NUM_MEM_CMDS];
459 /** The average latency of a demand MSHR miss. */
460 Stats::Formula demandAvgMshrMissLatency;
461 /** The average overall latency of an MSHR miss. */
462 Stats::Formula overallAvgMshrMissLatency;
464 /** The average latency of an MSHR miss, per command and thread. */
465 Stats::Formula avgMshrUncacheableLatency[MemCmd::NUM_MEM_CMDS];
466 /** The average overall latency of an MSHR miss. */
467 Stats::Formula overallAvgMshrUncacheableLatency;
469 /** The number of times a thread hit its MSHR cap. */
470 Stats::Vector mshr_cap_events;
471 /** The number of times software prefetches caused the MSHR to block. */
472 Stats::Vector soft_prefetch_mshr_full;
474 Stats::Scalar mshr_no_allocate_misses;
481 * Register stats for this object.
483 virtual void regStats();
486 BaseCache(const BaseCacheParams *p, unsigned blk_size);
491 virtual BaseMasterPort &getMasterPort(const std::string &if_name,
492 PortID idx = InvalidPortID);
493 virtual BaseSlavePort &getSlavePort(const std::string &if_name,
494 PortID idx = InvalidPortID);
497 * Query block size of a cache.
498 * @return The block size
507 Addr blockAlign(Addr addr) const { return (addr & ~(Addr(blkSize - 1))); }
510 const AddrRangeList &getAddrRanges() const { return addrRanges; }
512 MSHR *allocateMissBuffer(PacketPtr pkt, Tick time, bool sched_send = true)
514 return allocateBufferInternal(&mshrQueue,
515 blockAlign(pkt->getAddr()), blkSize,
516 pkt, time, sched_send);
519 MSHR *allocateWriteBuffer(PacketPtr pkt, Tick time)
521 // should only see writes or clean evicts here
522 assert(pkt->isWrite() || pkt->cmd == MemCmd::CleanEvict);
524 return allocateBufferInternal(&writeBuffer,
525 blockAlign(pkt->getAddr()), blkSize,
530 * Returns true if the cache is blocked for accesses.
532 bool isBlocked() const
538 * Marks the access path of the cache as blocked for the given cause. This
539 * also sets the blocked flag in the slave interface.
540 * @param cause The reason for the cache blocking.
542 void setBlocked(BlockedCause cause)
544 uint8_t flag = 1 << cause;
546 blocked_causes[cause]++;
547 blockedCycle = curCycle();
548 cpuSidePort->setBlocked();
551 DPRINTF(Cache,"Blocking for cause %d, mask=%d\n", cause, blocked);
555 * Marks the cache as unblocked for the given cause. This also clears the
556 * blocked flags in the appropriate interfaces.
557 * @param cause The newly unblocked cause.
558 * @warning Calling this function can cause a blocked request on the bus to
559 * access the cache. The cache must be in a state to handle that request.
561 void clearBlocked(BlockedCause cause)
563 uint8_t flag = 1 << cause;
565 DPRINTF(Cache,"Unblocking for cause %d, mask=%d\n", cause, blocked);
567 blocked_cycles[cause] += curCycle() - blockedCycle;
568 cpuSidePort->clearBlocked();
573 * Schedule a send event for the memory-side port. If already
574 * scheduled, this may reschedule the event at an earlier
575 * time. When the specified time is reached, the port is free to
576 * send either a response, a request, or a prefetch request.
578 * @param time The time when to attempt sending a packet.
580 void schedMemSideSendEvent(Tick time)
582 memSidePort->schedSendEvent(time);
585 virtual bool inCache(Addr addr, bool is_secure) const = 0;
587 virtual bool inMissQueue(Addr addr, bool is_secure) const = 0;
589 void incMissCount(PacketPtr pkt)
591 assert(pkt->req->masterId() < system->maxMasters());
592 misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
593 pkt->req->incAccessDepth();
597 exitSimLoop("A cache reached the maximum miss count");
600 void incHitCount(PacketPtr pkt)
602 assert(pkt->req->masterId() < system->maxMasters());
603 hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
609 #endif //__MEM_CACHE_BASE_HH__