diff options
Diffstat (limited to 'src/mem/cache/prefetch')
-rw-r--r-- | src/mem/cache/prefetch/base.cc | 160 | ||||
-rw-r--r-- | src/mem/cache/prefetch/base.hh | 42 | ||||
-rw-r--r-- | src/mem/cache/prefetch/ghb.cc | 40 | ||||
-rw-r--r-- | src/mem/cache/prefetch/ghb.hh | 10 | ||||
-rw-r--r-- | src/mem/cache/prefetch/stride.cc | 136 | ||||
-rw-r--r-- | src/mem/cache/prefetch/stride.hh | 34 | ||||
-rw-r--r-- | src/mem/cache/prefetch/tagged.cc | 19 |
7 files changed, 258 insertions, 183 deletions
diff --git a/src/mem/cache/prefetch/base.cc b/src/mem/cache/prefetch/base.cc index fcc02ff28..365ce6727 100644 --- a/src/mem/cache/prefetch/base.cc +++ b/src/mem/cache/prefetch/base.cc @@ -33,6 +33,7 @@ * Hardware Prefetcher Definition. */ +#include "arch/isa_traits.hh" #include "base/trace.hh" #include "mem/cache/base.hh" #include "mem/cache/prefetch/base.hh" @@ -43,7 +44,7 @@ BasePrefetcher::BasePrefetcher(const BaseCacheParams *p) : size(p->prefetcher_size), pageStop(!p->prefetch_past_page), serialSquash(p->prefetch_serial_squash), cacheCheckPush(p->prefetch_cache_check_push), - only_data(p->prefetch_data_accesses_only) + onlyData(p->prefetch_data_accesses_only) { } @@ -52,6 +53,7 @@ BasePrefetcher::setCache(BaseCache *_cache) { cache = _cache; blkSize = cache->getBlockSize(); + _name = cache->name() + "-pf"; } void @@ -99,7 +101,8 @@ BasePrefetcher::regStats(const std::string &name) pfSquashed .name(name + ".prefetcher.num_hwpf_squashed_from_miss") - .desc("number of hwpf that got squashed due to a miss aborting calculation time") + .desc("number of hwpf that got squashed due to a miss " + "aborting calculation time") ; } @@ -126,60 +129,79 @@ BasePrefetcher::inMissQueue(Addr addr) PacketPtr BasePrefetcher::getPacket() { - DPRINTF(HWPrefetch, "%s:Requesting a hw_pf to issue\n", cache->name()); + DPRINTF(HWPrefetch, "Requesting a hw_pf to issue\n"); if (pf.empty()) { - DPRINTF(HWPrefetch, "%s:No HW_PF found\n", cache->name()); + DPRINTF(HWPrefetch, "No HW_PF found\n"); return NULL; } PacketPtr pkt; - bool keepTrying = false; + bool keep_trying = false; do { pkt = *pf.begin(); pf.pop_front(); if (!cacheCheckPush) { - keepTrying = cache->inCache(pkt->getAddr()); + keep_trying = cache->inCache(pkt->getAddr()); } + + if (keep_trying) { + DPRINTF(HWPrefetch, "addr 0x%x in cache, skipping\n", + pkt->getAddr()); + delete pkt->req; + delete pkt; + } + if (pf.empty()) { cache->deassertMemSideBusRequest(BaseCache::Request_PF); - if (keepTrying) return NULL; //None left, all were in cache + if (keep_trying) { + return NULL; // None left, all were in cache + } } - } while (keepTrying); + } while (keep_trying); pfIssued++; + assert(pkt != NULL); + DPRINTF(HWPrefetch, "returning 0x%x\n", pkt->getAddr()); return pkt; } -void -BasePrefetcher::handleMiss(PacketPtr &pkt, Tick time) + +Tick +BasePrefetcher::notify(PacketPtr &pkt, Tick time) { - if (!pkt->req->isUncacheable() && !(pkt->req->isInstRead() && only_data)) - { - //Calculate the blk address - Addr blkAddr = pkt->getAddr() & ~(Addr)(blkSize-1); + if (!pkt->req->isUncacheable() && !(pkt->req->isInstRead() && onlyData)) { + // Calculate the blk address + Addr blk_addr = pkt->getAddr() & ~(Addr)(blkSize-1); - //Check if miss is in pfq, if so remove it - std::list<PacketPtr>::iterator iter = inPrefetch(blkAddr); + // Check if miss is in pfq, if so remove it + std::list<PacketPtr>::iterator iter = inPrefetch(blk_addr); if (iter != pf.end()) { - DPRINTF(HWPrefetch, "%s:Saw a miss to a queued prefetch, removing it\n", cache->name()); + DPRINTF(HWPrefetch, "Saw a miss to a queued prefetch addr: " + "0x%x, removing it\n", blk_addr); pfRemovedMSHR++; + delete (*iter)->req; + delete (*iter); pf.erase(iter); if (pf.empty()) cache->deassertMemSideBusRequest(BaseCache::Request_PF); } - //Remove anything in queue with delay older than time - //since everything is inserted in time order, start from end - //and work until pf.empty() or time is earlier - //This is done to emulate Aborting the previous work on a new miss - //Needed for serial calculators like GHB + // Remove anything in queue with delay older than time + // since everything is inserted in time order, start from end + // and work until pf.empty() or time is earlier + // This is done to emulate Aborting the previous work on a new miss + // Needed for serial calculators like GHB if (serialSquash) { iter = pf.end(); iter--; while (!pf.empty() && ((*iter)->time >= time)) { pfSquashed++; - pf.pop_back(); + DPRINTF(HWPrefetch, "Squashing old prefetch addr: 0x%x\n", + (*iter)->getAddr()); + delete (*iter)->req; + delete (*iter); + pf.erase(iter); iter--; } if (pf.empty()) @@ -191,74 +213,70 @@ BasePrefetcher::handleMiss(PacketPtr &pkt, Tick time) std::list<Tick> delays; calculatePrefetch(pkt, addresses, delays); - std::list<Addr>::iterator addr = addresses.begin(); - std::list<Tick>::iterator delay = delays.begin(); - while (addr != addresses.end()) - { - DPRINTF(HWPrefetch, "%s:Found a pf canidate, inserting into prefetch queue\n", cache->name()); - //temp calc this here... + std::list<Addr>::iterator addrIter = addresses.begin(); + std::list<Tick>::iterator delayIter = delays.begin(); + for (; addrIter != addresses.end(); ++addrIter, ++delayIter) { + Addr addr = *addrIter; + pfIdentified++; - //create a prefetch memreq - Request * prefetchReq = new Request(*addr, blkSize, 0); - PacketPtr prefetch; - prefetch = new Packet(prefetchReq, MemCmd::HardPFReq, -1); - prefetch->allocate(); - prefetch->req->setThreadContext(pkt->req->getCpuNum(), - pkt->req->getThreadNum()); - - prefetch->time = time + (*delay); //@todo ADD LATENCY HERE - //... initialize - - //Check if it is already in the cache - if (cacheCheckPush) { - if (cache->inCache(prefetch->getAddr())) { - addr++; - delay++; - continue; - } + + DPRINTF(HWPrefetch, "Found a pf candidate addr: 0x%x, " + "inserting into prefetch queue with delay %d time %d\n", + addr, *delayIter, time); + + // Check if it is already in the cache + if (cacheCheckPush && cache->inCache(addr)) { + DPRINTF(HWPrefetch, "Prefetch addr already in cache\n"); + continue; } - //Check if it is already in the miss_queue - if (cache->inMissQueue(prefetch->getAddr())) { - addr++; - delay++; + // Check if it is already in the miss_queue + if (cache->inMissQueue(addr)) { + DPRINTF(HWPrefetch, "Prefetch addr already in miss queue\n"); continue; } - //Check if it is already in the pf buffer - if (inPrefetch(prefetch->getAddr()) != pf.end()) { + // Check if it is already in the pf buffer + if (inPrefetch(addr) != pf.end()) { pfBufferHit++; - addr++; - delay++; + DPRINTF(HWPrefetch, "Prefetch addr already in pf buffer\n"); continue; } - //We just remove the head if we are full - if (pf.size() == size) - { - DPRINTF(HWPrefetch, "%s:Inserting into prefetch queue, it was full removing oldest\n", cache->name()); + // create a prefetch memreq + Request *prefetchReq = new Request(*addrIter, blkSize, 0); + PacketPtr prefetch = + new Packet(prefetchReq, MemCmd::HardPFReq, Packet::Broadcast); + prefetch->allocate(); + prefetch->req->setThreadContext(pkt->req->contextId(), + pkt->req->threadId()); + + prefetch->time = time + (*delayIter); // @todo ADD LATENCY HERE + + // We just remove the head if we are full + if (pf.size() == size) { pfRemovedFull++; + PacketPtr old_pkt = *pf.begin(); + DPRINTF(HWPrefetch, "Prefetch queue full, " + "removing oldest 0x%x\n", old_pkt->getAddr()); + delete old_pkt->req; + delete old_pkt; pf.pop_front(); } pf.push_back(prefetch); - - //Make sure to request the bus, with proper delay - cache->requestMemSideBus(BaseCache::Request_PF, prefetch->time); - - //Increment through the list - addr++; - delay++; } } + + return pf.empty() ? 0 : pf.front()->time; } std::list<PacketPtr>::iterator BasePrefetcher::inPrefetch(Addr address) { - //Guaranteed to only be one match, we always check before inserting + // Guaranteed to only be one match, we always check before inserting std::list<PacketPtr>::iterator iter; - for (iter=pf.begin(); iter != pf.end(); iter++) { + for (iter = pf.begin(); iter != pf.end(); iter++) { if (((*iter)->getAddr() & ~(Addr)(blkSize-1)) == address) { return iter; } @@ -266,4 +284,8 @@ BasePrefetcher::inPrefetch(Addr address) return pf.end(); } - +bool +BasePrefetcher::samePage(Addr a, Addr b) +{ + return roundDown(a, TheISA::VMPageSize) == roundDown(b, TheISA::VMPageSize); +} diff --git a/src/mem/cache/prefetch/base.hh b/src/mem/cache/prefetch/base.hh index 1515d8a93..fc027cb3b 100644 --- a/src/mem/cache/prefetch/base.hh +++ b/src/mem/cache/prefetch/base.hh @@ -73,30 +73,40 @@ class BasePrefetcher bool cacheCheckPush; /** Do we prefetch on only data reads, or on inst reads as well. */ - bool only_data; + bool onlyData; + + std::string _name; public: - Stats::Scalar<> pfIdentified; - Stats::Scalar<> pfMSHRHit; - Stats::Scalar<> pfCacheHit; - Stats::Scalar<> pfBufferHit; - Stats::Scalar<> pfRemovedFull; - Stats::Scalar<> pfRemovedMSHR; - Stats::Scalar<> pfIssued; - Stats::Scalar<> pfSpanPage; - Stats::Scalar<> pfSquashed; + Stats::Scalar pfIdentified; + Stats::Scalar pfMSHRHit; + Stats::Scalar pfCacheHit; + Stats::Scalar pfBufferHit; + Stats::Scalar pfRemovedFull; + Stats::Scalar pfRemovedMSHR; + Stats::Scalar pfIssued; + Stats::Scalar pfSpanPage; + Stats::Scalar pfSquashed; void regStats(const std::string &name); public: + BasePrefetcher(const BaseCacheParams *p); virtual ~BasePrefetcher() {} + const std::string name() const { return _name; } + void setCache(BaseCache *_cache); - void handleMiss(PacketPtr &pkt, Tick time); + /** + * Notify prefetcher of cache access (may be any access or just + * misses, depending on cache parameters.) + * @retval Time of next prefetch availability, or 0 if none. + */ + Tick notify(PacketPtr &pkt, Tick time); bool inCache(Addr addr); @@ -109,11 +119,21 @@ class BasePrefetcher return !pf.empty(); } + Tick nextPrefetchReadyTime() + { + return pf.empty() ? MaxTick : pf.front()->time; + } + virtual void calculatePrefetch(PacketPtr &pkt, std::list<Addr> &addresses, std::list<Tick> &delays) = 0; std::list<PacketPtr>::iterator inPrefetch(Addr address); + + /** + * Utility function: are addresses a and b on the same VM page? + */ + bool samePage(Addr a, Addr b); }; diff --git a/src/mem/cache/prefetch/ghb.cc b/src/mem/cache/prefetch/ghb.cc index f5b88e1a6..f8f7de1db 100644 --- a/src/mem/cache/prefetch/ghb.cc +++ b/src/mem/cache/prefetch/ghb.cc @@ -34,39 +34,37 @@ * GHB Prefetcher implementation. */ +#include "base/trace.hh" #include "mem/cache/prefetch/ghb.hh" -#include "arch/isa_traits.hh" void GHBPrefetcher::calculatePrefetch(PacketPtr &pkt, std::list<Addr> &addresses, std::list<Tick> &delays) { - Addr blkAddr = pkt->getAddr() & ~(Addr)(this->blkSize-1); - int cpuID = pkt->req->getCpuNum(); - if (!useCPUId) cpuID = 0; + if (useContextId && !pkt->req->hasContextId()) { + DPRINTF(HWPrefetch, "ignoring request with no context ID"); + return; + } + Addr blk_addr = pkt->getAddr() & ~(Addr)(blkSize-1); + int ctx_id = useContextId ? pkt->req->contextId() : 0; + assert(ctx_id < Max_Contexts); - int new_stride = blkAddr - last_miss_addr[cpuID]; - int old_stride = last_miss_addr[cpuID] - - second_last_miss_addr[cpuID]; + int new_stride = blk_addr - lastMissAddr[ctx_id]; + int old_stride = lastMissAddr[ctx_id] - secondLastMissAddr[ctx_id]; - second_last_miss_addr[cpuID] = last_miss_addr[cpuID]; - last_miss_addr[cpuID] = blkAddr; + secondLastMissAddr[ctx_id] = lastMissAddr[ctx_id]; + lastMissAddr[ctx_id] = blk_addr; if (new_stride == old_stride) { - for (int d=1; d <= degree; d++) { - Addr newAddr = blkAddr + d * new_stride; - if (this->pageStop && - (blkAddr & ~(TheISA::VMPageSize - 1)) != - (newAddr & ~(TheISA::VMPageSize - 1))) - { - //Spanned the page, so now stop - this->pfSpanPage += degree - d + 1; + for (int d = 1; d <= degree; d++) { + Addr new_addr = blk_addr + d * new_stride; + if (pageStop && !samePage(blk_addr, new_addr)) { + // Spanned the page, so now stop + pfSpanPage += degree - d + 1; return; - } - else - { - addresses.push_back(newAddr); + } else { + addresses.push_back(new_addr); delays.push_back(latency); } } diff --git a/src/mem/cache/prefetch/ghb.hh b/src/mem/cache/prefetch/ghb.hh index 4fb692016..c85221a39 100644 --- a/src/mem/cache/prefetch/ghb.hh +++ b/src/mem/cache/prefetch/ghb.hh @@ -42,18 +42,20 @@ class GHBPrefetcher : public BasePrefetcher { protected: - Addr second_last_miss_addr[64/*MAX_CPUS*/]; - Addr last_miss_addr[64/*MAX_CPUS*/]; + static const int Max_Contexts = 64; + + Addr secondLastMissAddr[Max_Contexts]; + Addr lastMissAddr[Max_Contexts]; Tick latency; int degree; - bool useCPUId; + bool useContextId; public: GHBPrefetcher(const BaseCacheParams *p) : BasePrefetcher(p), latency(p->prefetch_latency), - degree(p->prefetch_degree), useCPUId(p->prefetch_use_cpu_id) + degree(p->prefetch_degree), useContextId(p->prefetch_use_cpu_id) { } diff --git a/src/mem/cache/prefetch/stride.cc b/src/mem/cache/prefetch/stride.cc index b116b66c7..8af4e615e 100644 --- a/src/mem/cache/prefetch/stride.cc +++ b/src/mem/cache/prefetch/stride.cc @@ -34,59 +34,97 @@ * Stride Prefetcher template instantiations. */ +#include "base/trace.hh" #include "mem/cache/prefetch/stride.hh" void StridePrefetcher::calculatePrefetch(PacketPtr &pkt, std::list<Addr> &addresses, std::list<Tick> &delays) { -// Addr blkAddr = pkt->paddr & ~(Addr)(this->blkSize-1); - int cpuID = pkt->req->getCpuNum(); - if (!useCPUId) cpuID = 0; - - /* Scan Table for IAddr Match */ -/* std::list<strideEntry*>::iterator iter; - for (iter=table[cpuID].begin(); - iter !=table[cpuID].end(); - iter++) { - if ((*iter)->IAddr == pkt->pc) break; - } - - if (iter != table[cpuID].end()) { - //Hit in table - - int newStride = blkAddr - (*iter)->MAddr; - if (newStride == (*iter)->stride) { - (*iter)->confidence++; - } - else { - (*iter)->stride = newStride; - (*iter)->confidence--; - } - - (*iter)->MAddr = blkAddr; - - for (int d=1; d <= degree; d++) { - Addr newAddr = blkAddr + d * newStride; - if (this->pageStop && - (blkAddr & ~(TheISA::VMPageSize - 1)) != - (newAddr & ~(TheISA::VMPageSize - 1))) - { - //Spanned the page, so now stop - this->pfSpanPage += degree - d + 1; - return; - } - else - { - addresses.push_back(newAddr); - delays.push_back(latency); - } - } - } - else { - //Miss in table - //Find lowest confidence and replace - - } -*/ + if (!pkt->req->hasPC()) { + DPRINTF(HWPrefetch, "ignoring request with no PC"); + return; + } + + if (useContextId && !pkt->req->hasContextId()) { + DPRINTF(HWPrefetch, "ignoring request with no context ID"); + return; + } + + Addr blk_addr = pkt->getAddr() & ~(Addr)(blkSize-1); + int ctx_id = useContextId ? pkt->req->contextId() : 0; + Addr pc = pkt->req->getPC(); + assert(ctx_id < Max_Contexts); + std::list<StrideEntry*> &tab = table[ctx_id]; + + /* Scan Table for instAddr Match */ + std::list<StrideEntry*>::iterator iter; + for (iter = tab.begin(); iter != tab.end(); iter++) { + if ((*iter)->instAddr == pc) + break; + } + + if (iter != tab.end()) { + // Hit in table + + int new_stride = blk_addr - (*iter)->missAddr; + bool stride_match = (new_stride == (*iter)->stride); + + if (stride_match && new_stride != 0) { + if ((*iter)->confidence < Max_Conf) + (*iter)->confidence++; + } else { + (*iter)->stride = new_stride; + if ((*iter)->confidence > Min_Conf) + (*iter)->confidence = 0; + } + + DPRINTF(HWPrefetch, "hit: PC %x blk_addr %x stride %d (%s), conf %d\n", + pc, blk_addr, new_stride, stride_match ? "match" : "change", + (*iter)->confidence); + + (*iter)->missAddr = blk_addr; + + if ((*iter)->confidence <= 0) + return; + + for (int d = 1; d <= degree; d++) { + Addr new_addr = blk_addr + d * new_stride; + if (pageStop && !samePage(blk_addr, new_addr)) { + // Spanned the page, so now stop + pfSpanPage += degree - d + 1; + return; + } else { + DPRINTF(HWPrefetch, " queuing prefetch to %x @ %d\n", + new_addr, latency); + addresses.push_back(new_addr); + delays.push_back(latency); + } + } + } else { + // Miss in table + // Find lowest confidence and replace + + DPRINTF(HWPrefetch, "miss: PC %x blk_addr %x\n", pc, blk_addr); + + if (tab.size() >= 256) { //set default table size is 256 + std::list<StrideEntry*>::iterator min_pos = tab.begin(); + int min_conf = (*min_pos)->confidence; + for (iter = min_pos, ++iter; iter != tab.end(); ++iter) { + if ((*iter)->confidence < min_conf){ + min_pos = iter; + min_conf = (*iter)->confidence; + } + } + DPRINTF(HWPrefetch, " replacing PC %x\n", (*min_pos)->instAddr); + tab.erase(min_pos); + } + + StrideEntry *new_entry = new StrideEntry; + new_entry->instAddr = pc; + new_entry->missAddr = blk_addr; + new_entry->stride = 0; + new_entry->confidence = 0; + tab.push_back(new_entry); + } } diff --git a/src/mem/cache/prefetch/stride.hh b/src/mem/cache/prefetch/stride.hh index f6bdbc424..6ccd32b91 100644 --- a/src/mem/cache/prefetch/stride.hh +++ b/src/mem/cache/prefetch/stride.hh @@ -36,41 +36,41 @@ #ifndef __MEM_CACHE_PREFETCH_STRIDE_PREFETCHER_HH__ #define __MEM_CACHE_PREFETCH_STRIDE_PREFETCHER_HH__ +#include <limits.h> #include "mem/cache/prefetch/base.hh" class StridePrefetcher : public BasePrefetcher { protected: - class strideEntry + static const int Max_Contexts = 64; + + // These constants need to be changed with the type of the + // 'confidence' field below. + static const int Max_Conf = INT_MAX; + static const int Min_Conf = INT_MIN; + + class StrideEntry { public: - Addr IAddr; - Addr MAddr; + Addr instAddr; + Addr missAddr; int stride; - int64_t confidence; - -/* bool operator < (strideEntry a,strideEntry b) - { - if (a.confidence == b.confidence) { - return true; //?????? - } - else return a.confidence < b.confidence; - }*/ + int confidence; }; - Addr* lastMissAddr[64/*MAX_CPUS*/]; - std::list<strideEntry*> table[64/*MAX_CPUS*/]; + Addr *lastMissAddr[Max_Contexts]; + + std::list<StrideEntry*> table[Max_Contexts]; Tick latency; int degree; - bool useCPUId; - + bool useContextId; public: StridePrefetcher(const BaseCacheParams *p) : BasePrefetcher(p), latency(p->prefetch_latency), - degree(p->prefetch_degree), useCPUId(p->prefetch_use_cpu_id) + degree(p->prefetch_degree), useContextId(p->prefetch_use_cpu_id) { } diff --git a/src/mem/cache/prefetch/tagged.cc b/src/mem/cache/prefetch/tagged.cc index 6afe1c6c2..a6c2403ba 100644 --- a/src/mem/cache/prefetch/tagged.cc +++ b/src/mem/cache/prefetch/tagged.cc @@ -47,20 +47,15 @@ TaggedPrefetcher:: calculatePrefetch(PacketPtr &pkt, std::list<Addr> &addresses, std::list<Tick> &delays) { - Addr blkAddr = pkt->getAddr() & ~(Addr)(this->blkSize-1); + Addr blkAddr = pkt->getAddr() & ~(Addr)(blkSize-1); - for (int d=1; d <= degree; d++) { - Addr newAddr = blkAddr + d*(this->blkSize); - if (this->pageStop && - (blkAddr & ~(TheISA::VMPageSize - 1)) != - (newAddr & ~(TheISA::VMPageSize - 1))) - { - //Spanned the page, so now stop - this->pfSpanPage += degree - d + 1; + for (int d = 1; d <= degree; d++) { + Addr newAddr = blkAddr + d*(blkSize); + if (pageStop && !samePage(blkAddr, newAddr)) { + // Spanned the page, so now stop + pfSpanPage += degree - d + 1; return; - } - else - { + } else { addresses.push_back(newAddr); delays.push_back(latency); } |