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26 * this software without specific prior written permission.
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40 * Authors: Ron Dreslinski
45 #include "base/random.hh"
46 #include "mem/simple_mem.hh"
47 #include "debug/Drain.hh"
51 SimpleMemory::SimpleMemory(const SimpleMemoryParams
* p
) :
53 port(name() + ".port", *this), latency(p
->latency
),
54 latency_var(p
->latency_var
), bandwidth(p
->bandwidth
), isBusy(false),
55 retryReq(false), retryResp(false),
56 releaseEvent(this), dequeueEvent(this), drainManager(NULL
)
63 AbstractMemory::init();
65 // allow unconnected memories as this is used in several ruby
66 // systems at the moment
67 if (port
.isConnected()) {
68 port
.sendRangeChange();
73 SimpleMemory::recvAtomic(PacketPtr pkt
)
76 return pkt
->memInhibitAsserted() ? 0 : getLatency();
80 SimpleMemory::recvFunctional(PacketPtr pkt
)
82 pkt
->pushLabel(name());
84 functionalAccess(pkt
);
87 auto p
= packetQueue
.begin();
88 // potentially update the packets in our packet queue as well
89 while (!done
&& p
!= packetQueue
.end()) {
90 done
= pkt
->checkFunctional(p
->pkt
);
98 SimpleMemory::recvTimingReq(PacketPtr pkt
)
100 /// @todo temporary hack to deal with memory corruption issues until
101 /// 4-phase transactions are complete
102 for (int x
= 0; x
< pendingDelete
.size(); x
++)
103 delete pendingDelete
[x
];
104 pendingDelete
.clear();
106 if (pkt
->memInhibitAsserted()) {
107 // snooper will supply based on copy of packet
108 // still target's responsibility to delete packet
109 pendingDelete
.push_back(pkt
);
113 // we should never get a new request after committing to retry the
114 // current one, the bus violates the rule as it simply sends a
115 // retry to the next one waiting on the retry list, so simply
120 // if we are busy with a read or write, remember that we have to
127 // @todo someone should pay for this
128 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
130 // update the release time according to the bandwidth limit, and
131 // do so with respect to the time it takes to finish this request
132 // rather than long term as it is the short term data rate that is
133 // limited for any real memory
135 // only look at reads and writes when determining if we are busy,
136 // and for how long, as it is not clear what to regulate for the
137 // other types of commands
138 if (pkt
->isRead() || pkt
->isWrite()) {
139 // calculate an appropriate tick to release to not exceed
140 // the bandwidth limit
141 Tick duration
= pkt
->getSize() * bandwidth
;
143 // only consider ourselves busy if there is any need to wait
144 // to avoid extra events being scheduled for (infinitely) fast
147 schedule(releaseEvent
, curTick() + duration
);
152 // go ahead and deal with the packet and put the response in the
153 // queue if there is one
154 bool needsResponse
= pkt
->needsResponse();
156 // turn packet around to go back to requester if response expected
158 // recvAtomic() should already have turned packet into
160 assert(pkt
->isResponse());
161 // to keep things simple (and in order), we put the packet at
162 // the end even if the latency suggests it should be sent
163 // before the packet(s) before it
164 packetQueue
.emplace_back(DeferredPacket(pkt
, curTick() + getLatency()));
165 if (!retryResp
&& !dequeueEvent
.scheduled())
166 schedule(dequeueEvent
, packetQueue
.back().tick
);
168 pendingDelete
.push_back(pkt
);
175 SimpleMemory::release()
186 SimpleMemory::dequeue()
188 assert(!packetQueue
.empty());
189 DeferredPacket deferred_pkt
= packetQueue
.front();
191 retryResp
= !port
.sendTimingResp(deferred_pkt
.pkt
);
194 packetQueue
.pop_front();
196 // if the queue is not empty, schedule the next dequeue event,
197 // otherwise signal that we are drained if we were asked to do so
198 if (!packetQueue
.empty()) {
199 // if there were packets that got in-between then we
200 // already have an event scheduled, so use re-schedule
201 reschedule(dequeueEvent
,
202 std::max(packetQueue
.front().tick
, curTick()), true);
203 } else if (drainManager
) {
204 DPRINTF(Drain
, "Drainng of SimpleMemory complete\n");
205 drainManager
->signalDrainDone();
212 SimpleMemory::getLatency() const
215 (latency_var
? random_mt
.random
<Tick
>(0, latency_var
) : 0);
219 SimpleMemory::recvRespRetry()
227 SimpleMemory::getSlavePort(const std::string
&if_name
, PortID idx
)
229 if (if_name
!= "port") {
230 return MemObject::getSlavePort(if_name
, idx
);
237 SimpleMemory::drain(DrainManager
*dm
)
241 // also track our internal queue
242 if (!packetQueue
.empty()) {
245 DPRINTF(Drain
, "SimpleMemory Queue has requests, waiting to drain\n");
249 setDrainState(DrainState::Draining
);
251 setDrainState(DrainState::Drained
);
255 SimpleMemory::MemoryPort::MemoryPort(const std::string
& _name
,
256 SimpleMemory
& _memory
)
257 : SlavePort(_name
, &_memory
), memory(_memory
)
261 SimpleMemory::MemoryPort::getAddrRanges() const
263 AddrRangeList ranges
;
264 ranges
.push_back(memory
.getAddrRange());
269 SimpleMemory::MemoryPort::recvAtomic(PacketPtr pkt
)
271 return memory
.recvAtomic(pkt
);
275 SimpleMemory::MemoryPort::recvFunctional(PacketPtr pkt
)
277 memory
.recvFunctional(pkt
);
281 SimpleMemory::MemoryPort::recvTimingReq(PacketPtr pkt
)
283 return memory
.recvTimingReq(pkt
);
287 SimpleMemory::MemoryPort::recvRespRetry()
289 memory
.recvRespRetry();
293 SimpleMemoryParams::create()
295 return new SimpleMemory(this);