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47 * Definition of a crossbar object.
50 #include "base/misc.hh"
51 #include "base/trace.hh"
52 #include "debug/AddrRanges.hh"
53 #include "debug/CoherentXBar.hh"
54 #include "mem/coherent_xbar.hh"
55 #include "sim/system.hh"
57 CoherentXBar::CoherentXBar(const CoherentXBarParams
*p
)
58 : BaseXBar(p
), system(p
->system
), snoopFilter(p
->snoop_filter
),
59 snoopResponseLatency(p
->snoop_response_latency
)
61 // create the ports based on the size of the master and slave
62 // vector ports, and the presence of the default port, the ports
63 // are enumerated starting from zero
64 for (int i
= 0; i
< p
->port_master_connection_count
; ++i
) {
65 std::string portName
= csprintf("%s.master[%d]", name(), i
);
66 MasterPort
* bp
= new CoherentXBarMasterPort(portName
, *this, i
);
67 masterPorts
.push_back(bp
);
68 reqLayers
.push_back(new ReqLayer(*bp
, *this,
69 csprintf(".reqLayer%d", i
)));
70 snoopLayers
.push_back(new SnoopRespLayer(*bp
, *this,
71 csprintf(".snoopLayer%d", i
)));
74 // see if we have a default slave device connected and if so add
75 // our corresponding master port
76 if (p
->port_default_connection_count
) {
77 defaultPortID
= masterPorts
.size();
78 std::string portName
= name() + ".default";
79 MasterPort
* bp
= new CoherentXBarMasterPort(portName
, *this,
81 masterPorts
.push_back(bp
);
82 reqLayers
.push_back(new ReqLayer(*bp
, *this, csprintf(".reqLayer%d",
84 snoopLayers
.push_back(new SnoopRespLayer(*bp
, *this,
85 csprintf(".snoopLayer%d",
89 // create the slave ports, once again starting at zero
90 for (int i
= 0; i
< p
->port_slave_connection_count
; ++i
) {
91 std::string portName
= csprintf("%s.slave[%d]", name(), i
);
92 QueuedSlavePort
* bp
= new CoherentXBarSlavePort(portName
, *this, i
);
93 slavePorts
.push_back(bp
);
94 respLayers
.push_back(new RespLayer(*bp
, *this,
95 csprintf(".respLayer%d", i
)));
96 snoopRespPorts
.push_back(new SnoopRespPort(*bp
, *this));
100 snoopFilter
->setSlavePorts(slavePorts
);
105 CoherentXBar::~CoherentXBar()
107 for (auto l
: reqLayers
)
109 for (auto l
: respLayers
)
111 for (auto l
: snoopLayers
)
113 for (auto p
: snoopRespPorts
)
120 // the base class is responsible for determining the block size
123 // iterate over our slave ports and determine which of our
124 // neighbouring master ports are snooping and add them as snoopers
125 for (const auto& p
: slavePorts
) {
126 // check if the connected master port is snooping
127 if (p
->isSnooping()) {
128 DPRINTF(AddrRanges
, "Adding snooping master %s\n",
129 p
->getMasterPort().name());
130 snoopPorts
.push_back(p
);
134 if (snoopPorts
.empty())
135 warn("CoherentXBar %s has no snooping ports attached!\n", name());
139 CoherentXBar::recvTimingReq(PacketPtr pkt
, PortID slave_port_id
)
141 // @todo temporary hack to deal with memory corruption issue until
142 // 4-phase transactions are complete
143 for (int x
= 0; x
< pendingDelete
.size(); x
++)
144 delete pendingDelete
[x
];
145 pendingDelete
.clear();
147 // determine the source port based on the id
148 SlavePort
*src_port
= slavePorts
[slave_port_id
];
150 // remember if the packet is an express snoop
151 bool is_express_snoop
= pkt
->isExpressSnoop();
152 bool is_inhibited
= pkt
->memInhibitAsserted();
153 // for normal requests, going downstream, the express snoop flag
154 // and the inhibited flag should always be the same
155 assert(is_express_snoop
== is_inhibited
);
157 // determine the destination based on the address
158 PortID master_port_id
= findPort(pkt
->getAddr());
160 // test if the crossbar should be considered occupied for the current
161 // port, and exclude express snoops from the check
162 if (!is_express_snoop
&& !reqLayers
[master_port_id
]->tryTiming(src_port
)) {
163 DPRINTF(CoherentXBar
, "recvTimingReq: src %s %s 0x%x BUSY\n",
164 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
168 DPRINTF(CoherentXBar
, "recvTimingReq: src %s %s expr %d 0x%x\n",
169 src_port
->name(), pkt
->cmdString(), is_express_snoop
,
172 // store size and command as they might be modified when
173 // forwarding the packet
174 unsigned int pkt_size
= pkt
->hasData() ? pkt
->getSize() : 0;
175 unsigned int pkt_cmd
= pkt
->cmdToIndex();
177 // store the old header delay so we can restore it if needed
178 Tick old_header_delay
= pkt
->headerDelay
;
180 // a request sees the frontend and forward latency
181 Tick xbar_delay
= (frontendLatency
+ forwardLatency
) * clockPeriod();
183 // set the packet header and payload delay
184 calcPacketTiming(pkt
, xbar_delay
);
186 // determine how long to be crossbar layer is busy
187 Tick packetFinishTime
= clockEdge(Cycles(1)) + pkt
->payloadDelay
;
189 if (!system
->bypassCaches()) {
190 // the packet is a memory-mapped request and should be
191 // broadcasted to our snoopers but the source
193 // check with the snoop filter where to forward this packet
194 auto sf_res
= snoopFilter
->lookupRequest(pkt
, *src_port
);
195 // If SnoopFilter is enabled, the total time required by a packet
196 // to be delivered through the xbar has to be charged also with
197 // to lookup latency of the snoop filter (sf_res.second).
198 pkt
->headerDelay
+= sf_res
.second
* clockPeriod();
199 packetFinishTime
+= sf_res
.second
* clockPeriod();
200 DPRINTF(CoherentXBar
, "recvTimingReq: src %s %s 0x%x"\
201 " SF size: %i lat: %i\n", src_port
->name(),
202 pkt
->cmdString(), pkt
->getAddr(), sf_res
.first
.size(),
204 forwardTiming(pkt
, slave_port_id
, sf_res
.first
);
206 forwardTiming(pkt
, slave_port_id
);
210 // forwardTiming snooped into peer caches of the sender, and if
211 // this is a clean evict, but the packet is found in a cache, do
213 if (pkt
->cmd
== MemCmd::CleanEvict
&& pkt
->isBlockCached()) {
214 DPRINTF(CoherentXBar
, "recvTimingReq: Clean evict 0x%x still cached, "
215 "not forwarding\n", pkt
->getAddr());
217 // update the layer state and schedule an idle event
218 reqLayers
[master_port_id
]->succeededTiming(packetFinishTime
);
219 pendingDelete
.push_back(pkt
);
223 // remember if the packet will generate a snoop response
224 const bool expect_snoop_resp
= !is_inhibited
&& pkt
->memInhibitAsserted();
225 const bool expect_response
= pkt
->needsResponse() &&
226 !pkt
->memInhibitAsserted();
228 // Note: Cannot create a copy of the full packet, here.
229 MemCmd
orig_cmd(pkt
->cmd
);
231 // since it is a normal request, attempt to send the packet
232 bool success
= masterPorts
[master_port_id
]->sendTimingReq(pkt
);
234 if (snoopFilter
&& !system
->bypassCaches()) {
235 // The packet may already be overwritten by the sendTimingReq function.
236 // The snoop filter needs to see the original request *and* the return
237 // status of the send operation, so we need to recreate the original
238 // request. Atomic mode does not have the issue, as there the send
239 // operation and the response happen instantaneously and don't need two
241 MemCmd
tmp_cmd(pkt
->cmd
);
243 // Let the snoop filter know about the success of the send operation
244 snoopFilter
->updateRequest(pkt
, *src_port
, !success
);
248 // check if we were successful in sending the packet onwards
250 // express snoops and inhibited packets should never be forced
252 assert(!is_express_snoop
);
253 assert(!pkt
->memInhibitAsserted());
255 // restore the header delay
256 pkt
->headerDelay
= old_header_delay
;
258 DPRINTF(CoherentXBar
, "recvTimingReq: src %s %s 0x%x RETRY\n",
259 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
261 // update the layer state and schedule an idle event
262 reqLayers
[master_port_id
]->failedTiming(src_port
,
263 clockEdge(Cycles(1)));
265 // express snoops currently bypass the crossbar state entirely
266 if (!is_express_snoop
) {
267 // if this particular request will generate a snoop
269 if (expect_snoop_resp
) {
270 // we should never have an exsiting request outstanding
271 assert(outstandingSnoop
.find(pkt
->req
) ==
272 outstandingSnoop
.end());
273 outstandingSnoop
.insert(pkt
->req
);
275 // basic sanity check on the outstanding snoops
276 panic_if(outstandingSnoop
.size() > 512,
277 "Outstanding snoop requests exceeded 512\n");
280 // remember where to route the normal response to
281 if (expect_response
|| expect_snoop_resp
) {
282 assert(routeTo
.find(pkt
->req
) == routeTo
.end());
283 routeTo
[pkt
->req
] = slave_port_id
;
285 panic_if(routeTo
.size() > 512,
286 "Routing table exceeds 512 packets\n");
289 // update the layer state and schedule an idle event
290 reqLayers
[master_port_id
]->succeededTiming(packetFinishTime
);
293 // stats updates only consider packets that were successfully sent
294 pktCount
[slave_port_id
][master_port_id
]++;
295 pktSize
[slave_port_id
][master_port_id
] += pkt_size
;
296 transDist
[pkt_cmd
]++;
298 if (is_express_snoop
)
306 CoherentXBar::recvTimingResp(PacketPtr pkt
, PortID master_port_id
)
308 // determine the source port based on the id
309 MasterPort
*src_port
= masterPorts
[master_port_id
];
311 // determine the destination
312 const auto route_lookup
= routeTo
.find(pkt
->req
);
313 assert(route_lookup
!= routeTo
.end());
314 const PortID slave_port_id
= route_lookup
->second
;
315 assert(slave_port_id
!= InvalidPortID
);
316 assert(slave_port_id
< respLayers
.size());
318 // test if the crossbar should be considered occupied for the
320 if (!respLayers
[slave_port_id
]->tryTiming(src_port
)) {
321 DPRINTF(CoherentXBar
, "recvTimingResp: src %s %s 0x%x BUSY\n",
322 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
326 DPRINTF(CoherentXBar
, "recvTimingResp: src %s %s 0x%x\n",
327 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
329 // store size and command as they might be modified when
330 // forwarding the packet
331 unsigned int pkt_size
= pkt
->hasData() ? pkt
->getSize() : 0;
332 unsigned int pkt_cmd
= pkt
->cmdToIndex();
334 // a response sees the response latency
335 Tick xbar_delay
= responseLatency
* clockPeriod();
337 // set the packet header and payload delay
338 calcPacketTiming(pkt
, xbar_delay
);
340 // determine how long to be crossbar layer is busy
341 Tick packetFinishTime
= clockEdge(Cycles(1)) + pkt
->payloadDelay
;
343 if (snoopFilter
&& !system
->bypassCaches()) {
344 // let the snoop filter inspect the response and update its state
345 snoopFilter
->updateResponse(pkt
, *slavePorts
[slave_port_id
]);
348 // send the packet through the destination slave port and pay for
349 // any outstanding header delay
350 Tick latency
= pkt
->headerDelay
;
351 pkt
->headerDelay
= 0;
352 slavePorts
[slave_port_id
]->schedTimingResp(pkt
, curTick() + latency
);
354 // remove the request from the routing table
355 routeTo
.erase(route_lookup
);
357 respLayers
[slave_port_id
]->succeededTiming(packetFinishTime
);
360 pktCount
[slave_port_id
][master_port_id
]++;
361 pktSize
[slave_port_id
][master_port_id
] += pkt_size
;
362 transDist
[pkt_cmd
]++;
368 CoherentXBar::recvTimingSnoopReq(PacketPtr pkt
, PortID master_port_id
)
370 DPRINTF(CoherentXBar
, "recvTimingSnoopReq: src %s %s 0x%x\n",
371 masterPorts
[master_port_id
]->name(), pkt
->cmdString(),
374 // update stats here as we know the forwarding will succeed
375 transDist
[pkt
->cmdToIndex()]++;
378 // we should only see express snoops from caches
379 assert(pkt
->isExpressSnoop());
381 // remeber if the packet is inhibited so we can see if it changes
382 const bool is_inhibited
= pkt
->memInhibitAsserted();
385 // let the Snoop Filter work its magic and guide probing
386 auto sf_res
= snoopFilter
->lookupSnoop(pkt
);
387 // No timing here: packetFinishTime += sf_res.second * clockPeriod();
388 DPRINTF(CoherentXBar
, "recvTimingSnoopReq: src %s %s 0x%x"\
389 " SF size: %i lat: %i\n", masterPorts
[master_port_id
]->name(),
390 pkt
->cmdString(), pkt
->getAddr(), sf_res
.first
.size(),
393 // forward to all snoopers
394 forwardTiming(pkt
, InvalidPortID
, sf_res
.first
);
396 forwardTiming(pkt
, InvalidPortID
);
399 // if we can expect a response, remember how to route it
400 if (!is_inhibited
&& pkt
->memInhibitAsserted()) {
401 assert(routeTo
.find(pkt
->req
) == routeTo
.end());
402 routeTo
[pkt
->req
] = master_port_id
;
405 // a snoop request came from a connected slave device (one of
406 // our master ports), and if it is not coming from the slave
407 // device responsible for the address range something is
408 // wrong, hence there is nothing further to do as the packet
409 // would be going back to where it came from
410 assert(master_port_id
== findPort(pkt
->getAddr()));
414 CoherentXBar::recvTimingSnoopResp(PacketPtr pkt
, PortID slave_port_id
)
416 // determine the source port based on the id
417 SlavePort
* src_port
= slavePorts
[slave_port_id
];
419 // get the destination
420 const auto route_lookup
= routeTo
.find(pkt
->req
);
421 assert(route_lookup
!= routeTo
.end());
422 const PortID dest_port_id
= route_lookup
->second
;
423 assert(dest_port_id
!= InvalidPortID
);
425 // determine if the response is from a snoop request we
426 // created as the result of a normal request (in which case it
427 // should be in the outstandingSnoop), or if we merely forwarded
428 // someone else's snoop request
429 const bool forwardAsSnoop
= outstandingSnoop
.find(pkt
->req
) ==
430 outstandingSnoop
.end();
432 // test if the crossbar should be considered occupied for the
433 // current port, note that the check is bypassed if the response
434 // is being passed on as a normal response since this is occupying
435 // the response layer rather than the snoop response layer
436 if (forwardAsSnoop
) {
437 assert(dest_port_id
< snoopLayers
.size());
438 if (!snoopLayers
[dest_port_id
]->tryTiming(src_port
)) {
439 DPRINTF(CoherentXBar
, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n",
440 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
444 // get the master port that mirrors this slave port internally
445 MasterPort
* snoop_port
= snoopRespPorts
[slave_port_id
];
446 assert(dest_port_id
< respLayers
.size());
447 if (!respLayers
[dest_port_id
]->tryTiming(snoop_port
)) {
448 DPRINTF(CoherentXBar
, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n",
449 snoop_port
->name(), pkt
->cmdString(), pkt
->getAddr());
454 DPRINTF(CoherentXBar
, "recvTimingSnoopResp: src %s %s 0x%x\n",
455 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
457 // store size and command as they might be modified when
458 // forwarding the packet
459 unsigned int pkt_size
= pkt
->hasData() ? pkt
->getSize() : 0;
460 unsigned int pkt_cmd
= pkt
->cmdToIndex();
462 // responses are never express snoops
463 assert(!pkt
->isExpressSnoop());
465 // a snoop response sees the snoop response latency, and if it is
466 // forwarded as a normal response, the response latency
468 (forwardAsSnoop
? snoopResponseLatency
: responseLatency
) *
471 // set the packet header and payload delay
472 calcPacketTiming(pkt
, xbar_delay
);
474 // determine how long to be crossbar layer is busy
475 Tick packetFinishTime
= clockEdge(Cycles(1)) + pkt
->payloadDelay
;
477 // forward it either as a snoop response or a normal response
478 if (forwardAsSnoop
) {
479 // this is a snoop response to a snoop request we forwarded,
480 // e.g. coming from the L1 and going to the L2, and it should
481 // be forwarded as a snoop response
484 // update the probe filter so that it can properly track the line
485 snoopFilter
->updateSnoopForward(pkt
, *slavePorts
[slave_port_id
],
486 *masterPorts
[dest_port_id
]);
489 bool success M5_VAR_USED
=
490 masterPorts
[dest_port_id
]->sendTimingSnoopResp(pkt
);
491 pktCount
[slave_port_id
][dest_port_id
]++;
492 pktSize
[slave_port_id
][dest_port_id
] += pkt_size
;
495 snoopLayers
[dest_port_id
]->succeededTiming(packetFinishTime
);
497 // we got a snoop response on one of our slave ports,
498 // i.e. from a coherent master connected to the crossbar, and
499 // since we created the snoop request as part of recvTiming,
500 // this should now be a normal response again
501 outstandingSnoop
.erase(pkt
->req
);
503 // this is a snoop response from a coherent master, hence it
504 // should never go back to where the snoop response came from,
505 // but instead to where the original request came from
506 assert(slave_port_id
!= dest_port_id
);
509 // update the probe filter so that it can properly track the line
510 snoopFilter
->updateSnoopResponse(pkt
, *slavePorts
[slave_port_id
],
511 *slavePorts
[dest_port_id
]);
514 DPRINTF(CoherentXBar
, "recvTimingSnoopResp: src %s %s 0x%x"\
515 " FWD RESP\n", src_port
->name(), pkt
->cmdString(),
518 // as a normal response, it should go back to a master through
519 // one of our slave ports, we also pay for any outstanding
521 Tick latency
= pkt
->headerDelay
;
522 pkt
->headerDelay
= 0;
523 slavePorts
[dest_port_id
]->schedTimingResp(pkt
, curTick() + latency
);
525 respLayers
[dest_port_id
]->succeededTiming(packetFinishTime
);
528 // remove the request from the routing table
529 routeTo
.erase(route_lookup
);
532 transDist
[pkt_cmd
]++;
540 CoherentXBar::forwardTiming(PacketPtr pkt
, PortID exclude_slave_port_id
,
541 const std::vector
<QueuedSlavePort
*>& dests
)
543 DPRINTF(CoherentXBar
, "%s for %s address %x size %d\n", __func__
,
544 pkt
->cmdString(), pkt
->getAddr(), pkt
->getSize());
546 // snoops should only happen if the system isn't bypassing caches
547 assert(!system
->bypassCaches());
551 for (const auto& p
: dests
) {
552 // we could have gotten this request from a snooping master
553 // (corresponding to our own slave port that is also in
554 // snoopPorts) and should not send it back to where it came
556 if (exclude_slave_port_id
== InvalidPortID
||
557 p
->getId() != exclude_slave_port_id
) {
558 // cache is not allowed to refuse snoop
559 p
->sendTimingSnoopReq(pkt
);
564 // Stats for fanout of this forward operation
565 snoopFanout
.sample(fanout
);
569 CoherentXBar::recvReqRetry(PortID master_port_id
)
571 // responses and snoop responses never block on forwarding them,
572 // so the retry will always be coming from a port to which we
573 // tried to forward a request
574 reqLayers
[master_port_id
]->recvRetry();
578 CoherentXBar::recvAtomic(PacketPtr pkt
, PortID slave_port_id
)
580 DPRINTF(CoherentXBar
, "recvAtomic: packet src %s addr 0x%x cmd %s\n",
581 slavePorts
[slave_port_id
]->name(), pkt
->getAddr(),
584 unsigned int pkt_size
= pkt
->hasData() ? pkt
->getSize() : 0;
585 unsigned int pkt_cmd
= pkt
->cmdToIndex();
587 MemCmd snoop_response_cmd
= MemCmd::InvalidCmd
;
588 Tick snoop_response_latency
= 0;
590 if (!system
->bypassCaches()) {
591 // forward to all snoopers but the source
592 std::pair
<MemCmd
, Tick
> snoop_result
;
594 // check with the snoop filter where to forward this packet
596 snoopFilter
->lookupRequest(pkt
, *slavePorts
[slave_port_id
]);
597 snoop_response_latency
+= sf_res
.second
* clockPeriod();
598 DPRINTF(CoherentXBar
, "%s: src %s %s 0x%x"\
599 " SF size: %i lat: %i\n", __func__
,
600 slavePorts
[slave_port_id
]->name(), pkt
->cmdString(),
601 pkt
->getAddr(), sf_res
.first
.size(), sf_res
.second
);
602 snoop_result
= forwardAtomic(pkt
, slave_port_id
, InvalidPortID
,
605 snoop_result
= forwardAtomic(pkt
, slave_port_id
);
607 snoop_response_cmd
= snoop_result
.first
;
608 snoop_response_latency
+= snoop_result
.second
;
611 // even if we had a snoop response, we must continue and also
612 // perform the actual request at the destination
613 PortID master_port_id
= findPort(pkt
->getAddr());
615 // stats updates for the request
616 pktCount
[slave_port_id
][master_port_id
]++;
617 pktSize
[slave_port_id
][master_port_id
] += pkt_size
;
618 transDist
[pkt_cmd
]++;
620 // forward the request to the appropriate destination
621 Tick response_latency
= masterPorts
[master_port_id
]->sendAtomic(pkt
);
623 // Lower levels have replied, tell the snoop filter
624 if (snoopFilter
&& !system
->bypassCaches() && pkt
->isResponse()) {
625 snoopFilter
->updateResponse(pkt
, *slavePorts
[slave_port_id
]);
628 // if we got a response from a snooper, restore it here
629 if (snoop_response_cmd
!= MemCmd::InvalidCmd
) {
630 // no one else should have responded
631 assert(!pkt
->isResponse());
632 pkt
->cmd
= snoop_response_cmd
;
633 response_latency
= snoop_response_latency
;
636 // add the response data
637 if (pkt
->isResponse()) {
638 pkt_size
= pkt
->hasData() ? pkt
->getSize() : 0;
639 pkt_cmd
= pkt
->cmdToIndex();
642 pktCount
[slave_port_id
][master_port_id
]++;
643 pktSize
[slave_port_id
][master_port_id
] += pkt_size
;
644 transDist
[pkt_cmd
]++;
647 // @todo: Not setting header time
648 pkt
->payloadDelay
= response_latency
;
649 return response_latency
;
653 CoherentXBar::recvAtomicSnoop(PacketPtr pkt
, PortID master_port_id
)
655 DPRINTF(CoherentXBar
, "recvAtomicSnoop: packet src %s addr 0x%x cmd %s\n",
656 masterPorts
[master_port_id
]->name(), pkt
->getAddr(),
659 // add the request snoop data
662 // forward to all snoopers
663 std::pair
<MemCmd
, Tick
> snoop_result
;
664 Tick snoop_response_latency
= 0;
666 auto sf_res
= snoopFilter
->lookupSnoop(pkt
);
667 snoop_response_latency
+= sf_res
.second
* clockPeriod();
668 DPRINTF(CoherentXBar
, "%s: src %s %s 0x%x SF size: %i lat: %i\n",
669 __func__
, masterPorts
[master_port_id
]->name(), pkt
->cmdString(),
670 pkt
->getAddr(), sf_res
.first
.size(), sf_res
.second
);
671 snoop_result
= forwardAtomic(pkt
, InvalidPortID
, master_port_id
,
674 snoop_result
= forwardAtomic(pkt
, InvalidPortID
);
676 MemCmd snoop_response_cmd
= snoop_result
.first
;
677 snoop_response_latency
+= snoop_result
.second
;
679 if (snoop_response_cmd
!= MemCmd::InvalidCmd
)
680 pkt
->cmd
= snoop_response_cmd
;
682 // add the response snoop data
683 if (pkt
->isResponse()) {
687 // @todo: Not setting header time
688 pkt
->payloadDelay
= snoop_response_latency
;
689 return snoop_response_latency
;
692 std::pair
<MemCmd
, Tick
>
693 CoherentXBar::forwardAtomic(PacketPtr pkt
, PortID exclude_slave_port_id
,
694 PortID source_master_port_id
,
695 const std::vector
<QueuedSlavePort
*>& dests
)
697 // the packet may be changed on snoops, record the original
698 // command to enable us to restore it between snoops so that
699 // additional snoops can take place properly
700 MemCmd orig_cmd
= pkt
->cmd
;
701 MemCmd snoop_response_cmd
= MemCmd::InvalidCmd
;
702 Tick snoop_response_latency
= 0;
704 // snoops should only happen if the system isn't bypassing caches
705 assert(!system
->bypassCaches());
709 for (const auto& p
: dests
) {
710 // we could have gotten this request from a snooping master
711 // (corresponding to our own slave port that is also in
712 // snoopPorts) and should not send it back to where it came
714 if (exclude_slave_port_id
!= InvalidPortID
&&
715 p
->getId() == exclude_slave_port_id
)
718 Tick latency
= p
->sendAtomicSnoop(pkt
);
721 // in contrast to a functional access, we have to keep on
722 // going as all snoopers must be updated even if we get a
724 if (!pkt
->isResponse())
727 // response from snoop agent
728 assert(pkt
->cmd
!= orig_cmd
);
729 assert(pkt
->memInhibitAsserted());
730 // should only happen once
731 assert(snoop_response_cmd
== MemCmd::InvalidCmd
);
732 // save response state
733 snoop_response_cmd
= pkt
->cmd
;
734 snoop_response_latency
= latency
;
737 // Handle responses by the snoopers and differentiate between
738 // responses to requests from above and snoops from below
739 if (source_master_port_id
!= InvalidPortID
) {
740 // Getting a response for a snoop from below
741 assert(exclude_slave_port_id
== InvalidPortID
);
742 snoopFilter
->updateSnoopForward(pkt
, *p
,
743 *masterPorts
[source_master_port_id
]);
745 // Getting a response for a request from above
746 assert(source_master_port_id
== InvalidPortID
);
747 snoopFilter
->updateSnoopResponse(pkt
, *p
,
748 *slavePorts
[exclude_slave_port_id
]);
751 // restore original packet state for remaining snoopers
756 snoopFanout
.sample(fanout
);
758 // the packet is restored as part of the loop and any potential
759 // snoop response is part of the returned pair
760 return std::make_pair(snoop_response_cmd
, snoop_response_latency
);
764 CoherentXBar::recvFunctional(PacketPtr pkt
, PortID slave_port_id
)
766 if (!pkt
->isPrint()) {
767 // don't do DPRINTFs on PrintReq as it clutters up the output
768 DPRINTF(CoherentXBar
,
769 "recvFunctional: packet src %s addr 0x%x cmd %s\n",
770 slavePorts
[slave_port_id
]->name(), pkt
->getAddr(),
774 if (!system
->bypassCaches()) {
775 // forward to all snoopers but the source
776 forwardFunctional(pkt
, slave_port_id
);
779 // there is no need to continue if the snooping has found what we
780 // were looking for and the packet is already a response
781 if (!pkt
->isResponse()) {
782 // since our slave ports are queued ports we need to check them as well
783 for (const auto& p
: slavePorts
) {
784 // if we find a response that has the data, then the
785 // downstream caches/memories may be out of date, so simply stop
787 if (p
->checkFunctional(pkt
)) {
788 if (pkt
->needsResponse())
794 PortID dest_id
= findPort(pkt
->getAddr());
796 masterPorts
[dest_id
]->sendFunctional(pkt
);
801 CoherentXBar::recvFunctionalSnoop(PacketPtr pkt
, PortID master_port_id
)
803 if (!pkt
->isPrint()) {
804 // don't do DPRINTFs on PrintReq as it clutters up the output
805 DPRINTF(CoherentXBar
,
806 "recvFunctionalSnoop: packet src %s addr 0x%x cmd %s\n",
807 masterPorts
[master_port_id
]->name(), pkt
->getAddr(),
811 // forward to all snoopers
812 forwardFunctional(pkt
, InvalidPortID
);
816 CoherentXBar::forwardFunctional(PacketPtr pkt
, PortID exclude_slave_port_id
)
818 // snoops should only happen if the system isn't bypassing caches
819 assert(!system
->bypassCaches());
821 for (const auto& p
: snoopPorts
) {
822 // we could have gotten this request from a snooping master
823 // (corresponding to our own slave port that is also in
824 // snoopPorts) and should not send it back to where it came
826 if (exclude_slave_port_id
== InvalidPortID
||
827 p
->getId() != exclude_slave_port_id
)
828 p
->sendFunctionalSnoop(pkt
);
830 // if we get a response we are done
831 if (pkt
->isResponse()) {
838 CoherentXBar::regStats()
840 // register the stats of the base class and our layers
841 BaseXBar::regStats();
842 for (auto l
: reqLayers
)
844 for (auto l
: respLayers
)
846 for (auto l
: snoopLayers
)
850 .name(name() + ".snoops")
851 .desc("Total snoops (count)")
855 .init(0, snoopPorts
.size(), 1)
856 .name(name() + ".snoop_fanout")
857 .desc("Request fanout histogram")
862 CoherentXBarParams::create()
864 return new CoherentXBar(this);