2 * Copyright (c) 2013 ARM Limited
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
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8 * to a hardware implementation of the functionality of the software
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14 * Copyright (c) 2005 The Regents of The University of Michigan
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18 * modification, are permitted provided that the following conditions are
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40 * Authors: Ron Dreslinski
45 * Hardware Prefetcher Definition.
50 #include "arch/isa_traits.hh"
51 #include "base/trace.hh"
52 #include "config/the_isa.hh"
53 #include "debug/HWPrefetch.hh"
54 #include "mem/cache/prefetch/base.hh"
55 #include "mem/cache/base.hh"
56 #include "mem/request.hh"
57 #include "sim/system.hh"
59 BasePrefetcher::BasePrefetcher(const Params
*p
)
60 : ClockedObject(p
), size(p
->size
), latency(p
->latency
), degree(p
->degree
),
61 useMasterId(p
->use_master_id
), pageStop(!p
->cross_pages
),
62 serialSquash(p
->serial_squash
), onlyData(p
->data_accesses_only
),
63 system(p
->sys
), masterId(system
->getMasterId(name()))
68 BasePrefetcher::setCache(BaseCache
*_cache
)
71 blkSize
= cache
->getBlockSize();
75 BasePrefetcher::regStats()
78 .name(name() + ".prefetcher.num_hwpf_identified")
79 .desc("number of hwpf identified")
83 .name(name() + ".prefetcher.num_hwpf_already_in_mshr")
84 .desc("number of hwpf that were already in mshr")
88 .name(name() + ".prefetcher.num_hwpf_already_in_cache")
89 .desc("number of hwpf that were already in the cache")
93 .name(name() + ".prefetcher.num_hwpf_already_in_prefetcher")
94 .desc("number of hwpf that were already in the prefetch queue")
98 .name(name() + ".prefetcher.num_hwpf_evicted")
99 .desc("number of hwpf removed due to no buffer left")
103 .name(name() + ".prefetcher.num_hwpf_removed_MSHR_hit")
104 .desc("number of hwpf removed because MSHR allocated")
108 .name(name() + ".prefetcher.num_hwpf_issued")
109 .desc("number of hwpf issued")
113 .name(name() + ".prefetcher.num_hwpf_span_page")
114 .desc("number of hwpf spanning a virtual page")
118 .name(name() + ".prefetcher.num_hwpf_squashed_from_miss")
119 .desc("number of hwpf that got squashed due to a miss "
120 "aborting calculation time")
125 BasePrefetcher::inCache(Addr addr
, bool is_secure
)
127 if (cache
->inCache(addr
, is_secure
)) {
135 BasePrefetcher::inMissQueue(Addr addr
, bool is_secure
)
137 if (cache
->inMissQueue(addr
, is_secure
)) {
145 BasePrefetcher::getPacket()
147 DPRINTF(HWPrefetch
, "Requesting a hw_pf to issue\n");
150 DPRINTF(HWPrefetch
, "No HW_PF found\n");
154 PacketPtr pkt
= pf
.begin()->pkt
;
155 while (!pf
.empty()) {
156 pkt
= pf
.begin()->pkt
;
159 Addr blk_addr
= pkt
->getAddr() & ~(Addr
)(blkSize
-1);
160 bool is_secure
= pkt
->isSecure();
162 if (!inCache(blk_addr
, is_secure
) && !inMissQueue(blk_addr
, is_secure
))
163 // we found a prefetch, return it
166 DPRINTF(HWPrefetch
, "addr 0x%x (%s) in cache, skipping\n",
167 pkt
->getAddr(), is_secure
? "s" : "ns");
172 cache
->deassertMemSideBusRequest(BaseCache::Request_PF
);
173 return NULL
; // None left, all were in cache
179 DPRINTF(HWPrefetch
, "returning 0x%x (%s)\n", pkt
->getAddr(),
180 pkt
->isSecure() ? "s" : "ns");
186 BasePrefetcher::notify(PacketPtr
&pkt
, Tick tick
)
188 if (!pkt
->req
->isUncacheable() && !(pkt
->req
->isInstFetch() && onlyData
)) {
189 // Calculate the blk address
190 Addr blk_addr
= pkt
->getAddr() & ~(Addr
)(blkSize
-1);
191 bool is_secure
= pkt
->isSecure();
193 // Check if miss is in pfq, if so remove it
194 std::list
<DeferredPacket
>::iterator iter
= inPrefetch(blk_addr
,
196 if (iter
!= pf
.end()) {
197 DPRINTF(HWPrefetch
, "Saw a miss to a queued prefetch addr: "
198 "0x%x (%s), removing it\n", blk_addr
,
199 is_secure
? "s" : "ns");
201 delete iter
->pkt
->req
;
203 iter
= pf
.erase(iter
);
205 cache
->deassertMemSideBusRequest(BaseCache::Request_PF
);
208 // Remove anything in queue with delay older than time
209 // since everything is inserted in time order, start from end
210 // and work until pf.empty() or time is earlier
211 // This is done to emulate Aborting the previous work on a new miss
212 // Needed for serial calculators like GHB
215 if (iter
!= pf
.begin())
217 while (!pf
.empty() && iter
->tick
>= tick
) {
219 DPRINTF(HWPrefetch
, "Squashing old prefetch addr: 0x%x\n",
220 iter
->pkt
->getAddr());
221 delete iter
->pkt
->req
;
223 iter
= pf
.erase(iter
);
224 if (iter
!= pf
.begin())
228 cache
->deassertMemSideBusRequest(BaseCache::Request_PF
);
232 std::list
<Addr
> addresses
;
233 std::list
<Cycles
> delays
;
234 calculatePrefetch(pkt
, addresses
, delays
);
236 std::list
<Addr
>::iterator addrIter
= addresses
.begin();
237 std::list
<Cycles
>::iterator delayIter
= delays
.begin();
238 for (; addrIter
!= addresses
.end(); ++addrIter
, ++delayIter
) {
239 Addr addr
= *addrIter
;
243 DPRINTF(HWPrefetch
, "Found a pf candidate addr: 0x%x, "
244 "inserting into prefetch queue with delay %d time %d\n",
245 addr
, *delayIter
, time
);
247 // Check if it is already in the pf buffer
248 if (inPrefetch(addr
, is_secure
) != pf
.end()) {
250 DPRINTF(HWPrefetch
, "Prefetch addr already in pf buffer\n");
254 // create a prefetch memreq
255 Request
*prefetchReq
= new Request(*addrIter
, blkSize
, 0, masterId
);
257 prefetchReq
->setFlags(Request::SECURE
);
258 prefetchReq
->taskId(ContextSwitchTaskId::Prefetcher
);
260 new Packet(prefetchReq
, MemCmd::HardPFReq
);
261 prefetch
->allocate();
262 prefetch
->req
->setThreadContext(pkt
->req
->contextId(),
263 pkt
->req
->threadId());
265 // We just remove the head if we are full
266 if (pf
.size() == size
) {
268 PacketPtr old_pkt
= pf
.begin()->pkt
;
269 DPRINTF(HWPrefetch
, "Prefetch queue full, "
270 "removing oldest 0x%x\n", old_pkt
->getAddr());
276 pf
.push_back(DeferredPacket(tick
+ clockPeriod() * *delayIter
,
281 return pf
.empty() ? 0 : pf
.front().tick
;
284 std::list
<BasePrefetcher::DeferredPacket
>::iterator
285 BasePrefetcher::inPrefetch(Addr address
, bool is_secure
)
287 // Guaranteed to only be one match, we always check before inserting
288 std::list
<DeferredPacket
>::iterator iter
;
289 for (iter
= pf
.begin(); iter
!= pf
.end(); iter
++) {
290 if (((*iter
).pkt
->getAddr() & ~(Addr
)(blkSize
-1)) == address
&&
291 (*iter
).pkt
->isSecure() == is_secure
) {
299 BasePrefetcher::samePage(Addr a
, Addr b
)
301 return roundDown(a
, TheISA::VMPageSize
) == roundDown(b
, TheISA::VMPageSize
);