2 * Copyright (c) 2005 The Regents of The University of Michigan
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28 * Authors: Ron Dreslinski
33 * Hardware Prefetcher Definition.
38 #include "arch/isa_traits.hh"
39 #include "base/trace.hh"
40 #include "config/the_isa.hh"
41 #include "debug/HWPrefetch.hh"
42 #include "mem/cache/prefetch/base.hh"
43 #include "mem/cache/base.hh"
44 #include "mem/request.hh"
45 #include "sim/system.hh"
47 BasePrefetcher::BasePrefetcher(const Params
*p
)
48 : SimObject(p
), size(p
->size
), latency(p
->latency
), degree(p
->degree
),
49 useMasterId(p
->use_master_id
), pageStop(!p
->cross_pages
),
50 serialSquash(p
->serial_squash
), onlyData(p
->data_accesses_only
),
51 system(p
->sys
), masterId(system
->getMasterId(name()))
56 BasePrefetcher::setCache(BaseCache
*_cache
)
59 blkSize
= cache
->getBlockSize();
63 BasePrefetcher::regStats()
66 .name(name() + ".prefetcher.num_hwpf_identified")
67 .desc("number of hwpf identified")
71 .name(name() + ".prefetcher.num_hwpf_already_in_mshr")
72 .desc("number of hwpf that were already in mshr")
76 .name(name() + ".prefetcher.num_hwpf_already_in_cache")
77 .desc("number of hwpf that were already in the cache")
81 .name(name() + ".prefetcher.num_hwpf_already_in_prefetcher")
82 .desc("number of hwpf that were already in the prefetch queue")
86 .name(name() + ".prefetcher.num_hwpf_evicted")
87 .desc("number of hwpf removed due to no buffer left")
91 .name(name() + ".prefetcher.num_hwpf_removed_MSHR_hit")
92 .desc("number of hwpf removed because MSHR allocated")
96 .name(name() + ".prefetcher.num_hwpf_issued")
97 .desc("number of hwpf issued")
101 .name(name() + ".prefetcher.num_hwpf_span_page")
102 .desc("number of hwpf spanning a virtual page")
106 .name(name() + ".prefetcher.num_hwpf_squashed_from_miss")
107 .desc("number of hwpf that got squashed due to a miss "
108 "aborting calculation time")
113 BasePrefetcher::inCache(Addr addr
)
115 if (cache
->inCache(addr
)) {
123 BasePrefetcher::inMissQueue(Addr addr
)
125 if (cache
->inMissQueue(addr
)) {
133 BasePrefetcher::getPacket()
135 DPRINTF(HWPrefetch
, "Requesting a hw_pf to issue\n");
138 DPRINTF(HWPrefetch
, "No HW_PF found\n");
142 PacketPtr pkt
= *pf
.begin();
143 while (!pf
.empty()) {
147 Addr blk_addr
= pkt
->getAddr() & ~(Addr
)(blkSize
-1);
149 if (!inCache(blk_addr
) && !inMissQueue(blk_addr
))
150 // we found a prefetch, return it
153 DPRINTF(HWPrefetch
, "addr 0x%x in cache, skipping\n", pkt
->getAddr());
158 cache
->deassertMemSideBusRequest(BaseCache::Request_PF
);
159 return NULL
; // None left, all were in cache
165 DPRINTF(HWPrefetch
, "returning 0x%x\n", pkt
->getAddr());
171 BasePrefetcher::notify(PacketPtr
&pkt
, Tick time
)
173 if (!pkt
->req
->isUncacheable() && !(pkt
->req
->isInstFetch() && onlyData
)) {
174 // Calculate the blk address
175 Addr blk_addr
= pkt
->getAddr() & ~(Addr
)(blkSize
-1);
177 // Check if miss is in pfq, if so remove it
178 std::list
<PacketPtr
>::iterator iter
= inPrefetch(blk_addr
);
179 if (iter
!= pf
.end()) {
180 DPRINTF(HWPrefetch
, "Saw a miss to a queued prefetch addr: "
181 "0x%x, removing it\n", blk_addr
);
187 cache
->deassertMemSideBusRequest(BaseCache::Request_PF
);
190 // Remove anything in queue with delay older than time
191 // since everything is inserted in time order, start from end
192 // and work until pf.empty() or time is earlier
193 // This is done to emulate Aborting the previous work on a new miss
194 // Needed for serial calculators like GHB
198 while (!pf
.empty() && ((*iter
)->time
>= time
)) {
200 DPRINTF(HWPrefetch
, "Squashing old prefetch addr: 0x%x\n",
208 cache
->deassertMemSideBusRequest(BaseCache::Request_PF
);
212 std::list
<Addr
> addresses
;
213 std::list
<Tick
> delays
;
214 calculatePrefetch(pkt
, addresses
, delays
);
216 std::list
<Addr
>::iterator addrIter
= addresses
.begin();
217 std::list
<Tick
>::iterator delayIter
= delays
.begin();
218 for (; addrIter
!= addresses
.end(); ++addrIter
, ++delayIter
) {
219 Addr addr
= *addrIter
;
223 DPRINTF(HWPrefetch
, "Found a pf candidate addr: 0x%x, "
224 "inserting into prefetch queue with delay %d time %d\n",
225 addr
, *delayIter
, time
);
227 // Check if it is already in the pf buffer
228 if (inPrefetch(addr
) != pf
.end()) {
230 DPRINTF(HWPrefetch
, "Prefetch addr already in pf buffer\n");
234 // create a prefetch memreq
235 Request
*prefetchReq
= new Request(*addrIter
, blkSize
, 0, masterId
);
237 new Packet(prefetchReq
, MemCmd::HardPFReq
, Packet::Broadcast
);
238 prefetch
->allocate();
239 prefetch
->req
->setThreadContext(pkt
->req
->contextId(),
240 pkt
->req
->threadId());
242 prefetch
->time
= time
+ (*delayIter
); // @todo ADD LATENCY HERE
244 // We just remove the head if we are full
245 if (pf
.size() == size
) {
247 PacketPtr old_pkt
= *pf
.begin();
248 DPRINTF(HWPrefetch
, "Prefetch queue full, "
249 "removing oldest 0x%x\n", old_pkt
->getAddr());
255 pf
.push_back(prefetch
);
259 return pf
.empty() ? 0 : pf
.front()->time
;
262 std::list
<PacketPtr
>::iterator
263 BasePrefetcher::inPrefetch(Addr address
)
265 // Guaranteed to only be one match, we always check before inserting
266 std::list
<PacketPtr
>::iterator iter
;
267 for (iter
= pf
.begin(); iter
!= pf
.end(); iter
++) {
268 if (((*iter
)->getAddr() & ~(Addr
)(blkSize
-1)) == address
) {
276 BasePrefetcher::samePage(Addr a
, Addr b
)
278 return roundDown(a
, TheISA::VMPageSize
) == roundDown(b
, TheISA::VMPageSize
);