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44 #include "mem/packet_queue.hh"
46 #include "base/trace.hh"
47 #include "debug/Drain.hh"
48 #include "debug/PacketQueue.hh"
50 PacketQueue::PacketQueue(EventManager
& _em
, const std::string
& _label
,
51 const std::string
& _sendEventName
,
53 bool disable_sanity_check
)
54 : em(_em
), sendEvent([this]{ processSendEvent(); }, _sendEventName
),
55 _disableSanityCheck(disable_sanity_check
),
56 forceOrder(force_order
),
57 label(_label
), waitingOnRetry(false)
61 PacketQueue::~PacketQueue()
68 DPRINTF(PacketQueue
, "Queue %s received retry\n", name());
69 assert(waitingOnRetry
);
70 waitingOnRetry
= false;
75 PacketQueue::hasAddr(Addr addr
) const
77 // caller is responsible for ensuring that all packets have the
79 for (const auto& p
: transmitList
) {
80 if (p
.pkt
->getAddr() == addr
)
87 PacketQueue::trySatisfyFunctional(PacketPtr pkt
)
89 pkt
->pushLabel(label
);
91 auto i
= transmitList
.begin();
94 while (!found
&& i
!= transmitList
.end()) {
95 // If the buffered packet contains data, and it overlaps the
96 // current packet, then update data
97 found
= pkt
->trySatisfyFunctional(i
->pkt
);
107 PacketQueue::schedSendTiming(PacketPtr pkt
, Tick when
)
109 DPRINTF(PacketQueue
, "%s for %s address %x size %d when %lu ord: %i\n",
110 __func__
, pkt
->cmdString(), pkt
->getAddr(), pkt
->getSize(), when
,
113 // we can still send a packet before the end of this tick
114 assert(when
>= curTick());
116 // express snoops should never be queued
117 assert(!pkt
->isExpressSnoop());
119 // add a very basic sanity check on the port to ensure the
120 // invisible buffer is not growing beyond reasonable limits
121 if (!_disableSanityCheck
&& transmitList
.size() > 100) {
122 panic("Packet queue %s has grown beyond 100 packets\n",
126 // we should either have an outstanding retry, or a send event
127 // scheduled, but there is an unfortunate corner case where the
128 // x86 page-table walker and timing CPU send out a new request as
129 // part of the receiving of a response (called by
130 // PacketQueue::sendDeferredPacket), in which we end up calling
131 // ourselves again before we had a chance to update waitingOnRetry
132 // assert(waitingOnRetry || sendEvent.scheduled());
134 // this belongs in the middle somewhere, so search from the end to
135 // order by tick; however, if forceOrder is set, also make sure
136 // not to re-order in front of some existing packet with the same
138 auto it
= transmitList
.end();
139 while (it
!= transmitList
.begin()) {
141 if ((forceOrder
&& it
->pkt
->getAddr() == pkt
->getAddr()) ||
143 // emplace inserts the element before the position pointed to by
144 // the iterator, so advance it one step
145 transmitList
.emplace(++it
, when
, pkt
);
149 // either the packet list is empty or this has to be inserted
150 // before every other packet
151 transmitList
.emplace_front(when
, pkt
);
152 schedSendEvent(when
);
156 PacketQueue::schedSendEvent(Tick when
)
158 // if we are waiting on a retry just hold off
159 if (waitingOnRetry
) {
160 DPRINTF(PacketQueue
, "Not scheduling send as waiting for retry\n");
161 assert(!sendEvent
.scheduled());
165 if (when
!= MaxTick
) {
166 // we cannot go back in time, and to be consistent we stick to
167 // one tick in the future
168 when
= std::max(when
, curTick() + 1);
169 // @todo Revisit the +1
171 if (!sendEvent
.scheduled()) {
172 em
.schedule(&sendEvent
, when
);
173 } else if (when
< sendEvent
.when()) {
174 // if the new time is earlier than when the event
175 // currently is scheduled, move it forward
176 em
.reschedule(&sendEvent
, when
);
179 // we get a MaxTick when there is no more to send, so if we're
180 // draining, we may be done at this point
181 if (drainState() == DrainState::Draining
&&
182 transmitList
.empty() && !sendEvent
.scheduled()) {
184 DPRINTF(Drain
, "PacketQueue done draining,"
185 "processing drain event\n");
192 PacketQueue::sendDeferredPacket()
195 assert(!waitingOnRetry
);
196 assert(deferredPacketReady());
198 DeferredPacket dp
= transmitList
.front();
200 // take the packet of the list before sending it, as sending of
201 // the packet in some cases causes a new packet to be enqueued
202 // (most notaly when responding to the timing CPU, leading to a
203 // new request hitting in the L1 icache, leading to a new
205 transmitList
.pop_front();
207 // use the appropriate implementation of sendTiming based on the
209 waitingOnRetry
= !sendTiming(dp
.pkt
);
211 // if we succeeded and are not waiting for a retry, schedule the
213 if (!waitingOnRetry
) {
214 schedSendEvent(deferredPacketReadyTime());
216 // put the packet back at the front of the list
217 transmitList
.emplace_front(dp
);
222 PacketQueue::processSendEvent()
224 assert(!waitingOnRetry
);
225 sendDeferredPacket();
231 if (transmitList
.empty()) {
232 return DrainState::Drained
;
234 DPRINTF(Drain
, "PacketQueue not drained\n");
235 return DrainState::Draining
;
239 ReqPacketQueue::ReqPacketQueue(EventManager
& _em
, MasterPort
& _masterPort
,
240 const std::string _label
)
241 : PacketQueue(_em
, _label
, name(_masterPort
, _label
)),
242 masterPort(_masterPort
)
247 ReqPacketQueue::sendTiming(PacketPtr pkt
)
249 return masterPort
.sendTimingReq(pkt
);
252 SnoopRespPacketQueue::SnoopRespPacketQueue(EventManager
& _em
,
253 MasterPort
& _masterPort
,
255 const std::string _label
)
256 : PacketQueue(_em
, _label
, name(_masterPort
, _label
), force_order
),
257 masterPort(_masterPort
)
262 SnoopRespPacketQueue::sendTiming(PacketPtr pkt
)
264 return masterPort
.sendTimingSnoopResp(pkt
);
267 RespPacketQueue::RespPacketQueue(EventManager
& _em
, SlavePort
& _slavePort
,
269 const std::string _label
)
270 : PacketQueue(_em
, _label
, name(_slavePort
, _label
), force_order
),
271 slavePort(_slavePort
)
276 RespPacketQueue::sendTiming(PacketPtr pkt
)
278 return slavePort
.sendTimingResp(pkt
);