1/*
2 * Copyright (c) 2011-2015 ARM Limited
3 * All rights reserved
4 *
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
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2006 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Ali Saidi
41 * Andreas Hansson
42 * William Wang
43 */
44
45/**
46 * @file
47 * Definition of a crossbar object.
48 */
49
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"
56
57CoherentXBar::CoherentXBar(const CoherentXBarParams *p)
58 : BaseXBar(p), system(p->system), snoopFilter(p->snoop_filter),
59 snoopResponseLatency(p->snoop_response_latency)
60{
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)));
72 }
73
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,
80 defaultPortID);
81 masterPorts.push_back(bp);
82 reqLayers.push_back(new ReqLayer(*bp, *this, csprintf(".reqLayer%d",
83 defaultPortID)));
84 snoopLayers.push_back(new SnoopRespLayer(*bp, *this,
85 csprintf(".snoopLayer%d",
86 defaultPortID)));
87 }
88
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 SlavePort* 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));
97 }
98
99 if (snoopFilter)
100 snoopFilter->setSlavePorts(slavePorts);
101
102 clearPortCache();
103}
104
105CoherentXBar::~CoherentXBar()
106{
107 for (auto l: reqLayers)
108 delete l;
109 for (auto l: respLayers)
110 delete l;
111 for (auto l: snoopLayers)
112 delete l;
113 for (auto p: snoopRespPorts)
114 delete p;
115}
116
117void
118CoherentXBar::init()
119{
120 // the base class is responsible for determining the block size
121 BaseXBar::init();
122
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);
131 }
132 }
133
134 if (snoopPorts.empty())
135 warn("CoherentXBar %s has no snooping ports attached!\n", name());
136}
137
138bool
139CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id)
140{
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();
146
147 // determine the source port based on the id
148 SlavePort *src_port = slavePorts[slave_port_id];
149
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);
156
157 // determine the destination based on the address
158 PortID master_port_id = findPort(pkt->getAddr());
159
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());
165 return false;
166 }
167
168 DPRINTF(CoherentXBar, "recvTimingReq: src %s %s expr %d 0x%x\n",
169 src_port->name(), pkt->cmdString(), is_express_snoop,
170 pkt->getAddr());
171
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();
176
177 // store the old header delay so we can restore it if needed
178 Tick old_header_delay = pkt->headerDelay;
179
180 // a request sees the frontend and forward latency
181 Tick xbar_delay = (frontendLatency + forwardLatency) * clockPeriod();
182
183 // set the packet header and payload delay
184 calcPacketTiming(pkt, xbar_delay);
185
186 // determine how long to be crossbar layer is busy
187 Tick packetFinishTime = clockEdge(Cycles(1)) + pkt->payloadDelay;
188
189 if (!system->bypassCaches()) {
190 // the packet is a memory-mapped request and should be
191 // broadcasted to our snoopers but the source
192 if (snoopFilter) {
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(),
203 sf_res.second);
204 forwardTiming(pkt, slave_port_id, sf_res.first);
205 } else {
206 forwardTiming(pkt, slave_port_id);
207 }
208 }
209
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
212 // not forward it
213 if (pkt->cmd == MemCmd::CleanEvict && pkt->isBlockCached()) {
214 DPRINTF(CoherentXBar, "recvTimingReq: Clean evict 0x%x still cached, "
215 "not forwarding\n", pkt->getAddr());
216
217 // update the layer state and schedule an idle event
218 reqLayers[master_port_id]->succeededTiming(packetFinishTime);
219 pendingDelete.push_back(pkt);
220 return true;
221 }
222
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();
227
228 // Note: Cannot create a copy of the full packet, here.
229 MemCmd orig_cmd(pkt->cmd);
230
231 // since it is a normal request, attempt to send the packet
232 bool success = masterPorts[master_port_id]->sendTimingReq(pkt);
233
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
240 // phase tracking.
241 MemCmd tmp_cmd(pkt->cmd);
242 pkt->cmd = orig_cmd;
243 // Let the snoop filter know about the success of the send operation
244 snoopFilter->updateRequest(pkt, *src_port, !success);
245 pkt->cmd = tmp_cmd;
246 }
247
248 // check if we were successful in sending the packet onwards
249 if (!success) {
250 // express snoops and inhibited packets should never be forced
251 // to retry
252 assert(!is_express_snoop);
253 assert(!pkt->memInhibitAsserted());
254
255 // restore the header delay
256 pkt->headerDelay = old_header_delay;
257
258 DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x RETRY\n",
259 src_port->name(), pkt->cmdString(), pkt->getAddr());
260
261 // update the layer state and schedule an idle event
262 reqLayers[master_port_id]->failedTiming(src_port,
263 clockEdge(Cycles(1)));
264 } else {
265 // express snoops currently bypass the crossbar state entirely
266 if (!is_express_snoop) {
267 // if this particular request will generate a snoop
268 // response
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);
274
275 // basic sanity check on the outstanding snoops
276 panic_if(outstandingSnoop.size() > 512,
277 "Outstanding snoop requests exceeded 512\n");
278 }
279
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;
284
285 panic_if(routeTo.size() > 512,
286 "Routing table exceeds 512 packets\n");
287 }
288
289 // update the layer state and schedule an idle event
290 reqLayers[master_port_id]->succeededTiming(packetFinishTime);
291 }
292
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]++;
297
298 if (is_express_snoop)
299 snoops++;
300 }
301
302 return success;
303}
304
305bool
306CoherentXBar::recvTimingResp(PacketPtr pkt, PortID master_port_id)
307{
308 // determine the source port based on the id
309 MasterPort *src_port = masterPorts[master_port_id];
310
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());
317
318 // test if the crossbar should be considered occupied for the
319 // current port
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());
323 return false;
324 }
325
326 DPRINTF(CoherentXBar, "recvTimingResp: src %s %s 0x%x\n",
327 src_port->name(), pkt->cmdString(), pkt->getAddr());
328
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();
333
334 // a response sees the response latency
335 Tick xbar_delay = responseLatency * clockPeriod();
336
337 // set the packet header and payload delay
338 calcPacketTiming(pkt, xbar_delay);
339
340 // determine how long to be crossbar layer is busy
341 Tick packetFinishTime = clockEdge(Cycles(1)) + pkt->payloadDelay;
342
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]);
346 }
347
348 // send the packet through the destination slave port
349 bool success M5_VAR_USED = slavePorts[slave_port_id]->sendTimingResp(pkt);
350
351 // currently it is illegal to block responses... can lead to
352 // deadlock
353 assert(success);
354
355 // remove the request from the routing table
356 routeTo.erase(route_lookup);
357
358 respLayers[slave_port_id]->succeededTiming(packetFinishTime);
359
360 // stats updates
361 pktCount[slave_port_id][master_port_id]++;
362 pktSize[slave_port_id][master_port_id] += pkt_size;
363 transDist[pkt_cmd]++;
364
365 return true;
366}
367
368void
369CoherentXBar::recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id)
370{
371 DPRINTF(CoherentXBar, "recvTimingSnoopReq: src %s %s 0x%x\n",
372 masterPorts[master_port_id]->name(), pkt->cmdString(),
373 pkt->getAddr());
374
375 // update stats here as we know the forwarding will succeed
376 transDist[pkt->cmdToIndex()]++;
377 snoops++;
378
379 // we should only see express snoops from caches
380 assert(pkt->isExpressSnoop());
381
382 // remeber if the packet is inhibited so we can see if it changes
383 const bool is_inhibited = pkt->memInhibitAsserted();
384
385 if (snoopFilter) {
386 // let the Snoop Filter work its magic and guide probing
387 auto sf_res = snoopFilter->lookupSnoop(pkt);
388 // No timing here: packetFinishTime += sf_res.second * clockPeriod();
389 DPRINTF(CoherentXBar, "recvTimingSnoopReq: src %s %s 0x%x"\
390 " SF size: %i lat: %i\n", masterPorts[master_port_id]->name(),
391 pkt->cmdString(), pkt->getAddr(), sf_res.first.size(),
392 sf_res.second);
393
394 // forward to all snoopers
395 forwardTiming(pkt, InvalidPortID, sf_res.first);
396 } else {
397 forwardTiming(pkt, InvalidPortID);
398 }
399
400 // if we can expect a response, remember how to route it
401 if (!is_inhibited && pkt->memInhibitAsserted()) {
402 assert(routeTo.find(pkt->req) == routeTo.end());
403 routeTo[pkt->req] = master_port_id;
404 }
405
406 // a snoop request came from a connected slave device (one of
407 // our master ports), and if it is not coming from the slave
408 // device responsible for the address range something is
409 // wrong, hence there is nothing further to do as the packet
410 // would be going back to where it came from
411 assert(master_port_id == findPort(pkt->getAddr()));
412}
413
414bool
415CoherentXBar::recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id)
416{
417 // determine the source port based on the id
418 SlavePort* src_port = slavePorts[slave_port_id];
419
420 // get the destination
421 const auto route_lookup = routeTo.find(pkt->req);
422 assert(route_lookup != routeTo.end());
423 const PortID dest_port_id = route_lookup->second;
424 assert(dest_port_id != InvalidPortID);
425
426 // determine if the response is from a snoop request we
427 // created as the result of a normal request (in which case it
428 // should be in the outstandingSnoop), or if we merely forwarded
429 // someone else's snoop request
430 const bool forwardAsSnoop = outstandingSnoop.find(pkt->req) ==
431 outstandingSnoop.end();
432
433 // test if the crossbar should be considered occupied for the
434 // current port, note that the check is bypassed if the response
435 // is being passed on as a normal response since this is occupying
436 // the response layer rather than the snoop response layer
437 if (forwardAsSnoop) {
438 assert(dest_port_id < snoopLayers.size());
439 if (!snoopLayers[dest_port_id]->tryTiming(src_port)) {
440 DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n",
441 src_port->name(), pkt->cmdString(), pkt->getAddr());
442 return false;
443 }
444 } else {
445 // get the master port that mirrors this slave port internally
446 MasterPort* snoop_port = snoopRespPorts[slave_port_id];
447 assert(dest_port_id < respLayers.size());
448 if (!respLayers[dest_port_id]->tryTiming(snoop_port)) {
449 DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n",
450 snoop_port->name(), pkt->cmdString(), pkt->getAddr());
451 return false;
452 }
453 }
454
455 DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x\n",
456 src_port->name(), pkt->cmdString(), pkt->getAddr());
457
458 // store size and command as they might be modified when
459 // forwarding the packet
460 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
461 unsigned int pkt_cmd = pkt->cmdToIndex();
462
463 // responses are never express snoops
464 assert(!pkt->isExpressSnoop());
465
466 // a snoop response sees the snoop response latency, and if it is
467 // forwarded as a normal response, the response latency
468 Tick xbar_delay =
469 (forwardAsSnoop ? snoopResponseLatency : responseLatency) *
470 clockPeriod();
471
472 // set the packet header and payload delay
473 calcPacketTiming(pkt, xbar_delay);
474
475 // determine how long to be crossbar layer is busy
476 Tick packetFinishTime = clockEdge(Cycles(1)) + pkt->payloadDelay;
477
478 // forward it either as a snoop response or a normal response
479 if (forwardAsSnoop) {
480 // this is a snoop response to a snoop request we forwarded,
481 // e.g. coming from the L1 and going to the L2, and it should
482 // be forwarded as a snoop response
483
484 if (snoopFilter) {
485 // update the probe filter so that it can properly track the line
486 snoopFilter->updateSnoopForward(pkt, *slavePorts[slave_port_id],
487 *masterPorts[dest_port_id]);
488 }
489
490 bool success M5_VAR_USED =
491 masterPorts[dest_port_id]->sendTimingSnoopResp(pkt);
492 pktCount[slave_port_id][dest_port_id]++;
493 pktSize[slave_port_id][dest_port_id] += pkt_size;
494 assert(success);
495
496 snoopLayers[dest_port_id]->succeededTiming(packetFinishTime);
497 } else {
498 // we got a snoop response on one of our slave ports,
499 // i.e. from a coherent master connected to the crossbar, and
500 // since we created the snoop request as part of recvTiming,
501 // this should now be a normal response again
502 outstandingSnoop.erase(pkt->req);
503
504 // this is a snoop response from a coherent master, hence it
505 // should never go back to where the snoop response came from,
506 // but instead to where the original request came from
507 assert(slave_port_id != dest_port_id);
508
509 if (snoopFilter) {
510 // update the probe filter so that it can properly track the line
511 snoopFilter->updateSnoopResponse(pkt, *slavePorts[slave_port_id],
512 *slavePorts[dest_port_id]);
513 }
514
515 DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x"\
516 " FWD RESP\n", src_port->name(), pkt->cmdString(),
517 pkt->getAddr());
518
519 // as a normal response, it should go back to a master through
520 // one of our slave ports, at this point we are ignoring the
521 // fact that the response layer could be busy and do not touch
522 // its state
523 bool success M5_VAR_USED =
524 slavePorts[dest_port_id]->sendTimingResp(pkt);
525
526 // @todo Put the response in an internal FIFO and pass it on
527 // to the response layer from there
528
529 // currently it is illegal to block responses... can lead
530 // to deadlock
531 assert(success);
532
533 respLayers[dest_port_id]->succeededTiming(packetFinishTime);
534 }
535
536 // remove the request from the routing table
537 routeTo.erase(route_lookup);
538
539 // stats updates
540 transDist[pkt_cmd]++;
541 snoops++;
542
543 return true;
544}
545
546
547void
548CoherentXBar::forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id,
549 const std::vector<SlavePort*>& dests)
550{
551 DPRINTF(CoherentXBar, "%s for %s address %x size %d\n", __func__,
552 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
553
554 // snoops should only happen if the system isn't bypassing caches
555 assert(!system->bypassCaches());
556
557 unsigned fanout = 0;
558
559 for (const auto& p: dests) {
560 // we could have gotten this request from a snooping master
561 // (corresponding to our own slave port that is also in
562 // snoopPorts) and should not send it back to where it came
563 // from
564 if (exclude_slave_port_id == InvalidPortID ||
565 p->getId() != exclude_slave_port_id) {
566 // cache is not allowed to refuse snoop
567 p->sendTimingSnoopReq(pkt);
568 fanout++;
569 }
570 }
571
572 // Stats for fanout of this forward operation
573 snoopFanout.sample(fanout);
574}
575
576void
577CoherentXBar::recvReqRetry(PortID master_port_id)
578{
579 // responses and snoop responses never block on forwarding them,
580 // so the retry will always be coming from a port to which we
581 // tried to forward a request
582 reqLayers[master_port_id]->recvRetry();
583}
584
585Tick
586CoherentXBar::recvAtomic(PacketPtr pkt, PortID slave_port_id)
587{
588 DPRINTF(CoherentXBar, "recvAtomic: packet src %s addr 0x%x cmd %s\n",
589 slavePorts[slave_port_id]->name(), pkt->getAddr(),
590 pkt->cmdString());
591
592 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
593 unsigned int pkt_cmd = pkt->cmdToIndex();
594
595 MemCmd snoop_response_cmd = MemCmd::InvalidCmd;
596 Tick snoop_response_latency = 0;
597
598 if (!system->bypassCaches()) {
599 // forward to all snoopers but the source
600 std::pair<MemCmd, Tick> snoop_result;
601 if (snoopFilter) {
602 // check with the snoop filter where to forward this packet
603 auto sf_res =
604 snoopFilter->lookupRequest(pkt, *slavePorts[slave_port_id]);
605 snoop_response_latency += sf_res.second * clockPeriod();
606 DPRINTF(CoherentXBar, "%s: src %s %s 0x%x"\
607 " SF size: %i lat: %i\n", __func__,
608 slavePorts[slave_port_id]->name(), pkt->cmdString(),
609 pkt->getAddr(), sf_res.first.size(), sf_res.second);
610 snoop_result = forwardAtomic(pkt, slave_port_id, InvalidPortID,
611 sf_res.first);
612 } else {
613 snoop_result = forwardAtomic(pkt, slave_port_id);
614 }
615 snoop_response_cmd = snoop_result.first;
616 snoop_response_latency += snoop_result.second;
617 }
618
619 // even if we had a snoop response, we must continue and also
620 // perform the actual request at the destination
621 PortID master_port_id = findPort(pkt->getAddr());
622
623 // stats updates for the request
624 pktCount[slave_port_id][master_port_id]++;
625 pktSize[slave_port_id][master_port_id] += pkt_size;
626 transDist[pkt_cmd]++;
627
628 // forward the request to the appropriate destination
629 Tick response_latency = masterPorts[master_port_id]->sendAtomic(pkt);
630
631 // Lower levels have replied, tell the snoop filter
632 if (snoopFilter && !system->bypassCaches() && pkt->isResponse()) {
633 snoopFilter->updateResponse(pkt, *slavePorts[slave_port_id]);
634 }
635
636 // if we got a response from a snooper, restore it here
637 if (snoop_response_cmd != MemCmd::InvalidCmd) {
638 // no one else should have responded
639 assert(!pkt->isResponse());
640 pkt->cmd = snoop_response_cmd;
641 response_latency = snoop_response_latency;
642 }
643
644 // add the response data
645 if (pkt->isResponse()) {
646 pkt_size = pkt->hasData() ? pkt->getSize() : 0;
647 pkt_cmd = pkt->cmdToIndex();
648
649 // stats updates
650 pktCount[slave_port_id][master_port_id]++;
651 pktSize[slave_port_id][master_port_id] += pkt_size;
652 transDist[pkt_cmd]++;
653 }
654
655 // @todo: Not setting header time
656 pkt->payloadDelay = response_latency;
657 return response_latency;
658}
659
660Tick
661CoherentXBar::recvAtomicSnoop(PacketPtr pkt, PortID master_port_id)
662{
663 DPRINTF(CoherentXBar, "recvAtomicSnoop: packet src %s addr 0x%x cmd %s\n",
664 masterPorts[master_port_id]->name(), pkt->getAddr(),
665 pkt->cmdString());
666
667 // add the request snoop data
668 snoops++;
669
670 // forward to all snoopers
671 std::pair<MemCmd, Tick> snoop_result;
672 Tick snoop_response_latency = 0;
673 if (snoopFilter) {
674 auto sf_res = snoopFilter->lookupSnoop(pkt);
675 snoop_response_latency += sf_res.second * clockPeriod();
676 DPRINTF(CoherentXBar, "%s: src %s %s 0x%x SF size: %i lat: %i\n",
677 __func__, masterPorts[master_port_id]->name(), pkt->cmdString(),
678 pkt->getAddr(), sf_res.first.size(), sf_res.second);
679 snoop_result = forwardAtomic(pkt, InvalidPortID, master_port_id,
680 sf_res.first);
681 } else {
682 snoop_result = forwardAtomic(pkt, InvalidPortID);
683 }
684 MemCmd snoop_response_cmd = snoop_result.first;
685 snoop_response_latency += snoop_result.second;
686
687 if (snoop_response_cmd != MemCmd::InvalidCmd)
688 pkt->cmd = snoop_response_cmd;
689
690 // add the response snoop data
691 if (pkt->isResponse()) {
692 snoops++;
693 }
694
695 // @todo: Not setting header time
696 pkt->payloadDelay = snoop_response_latency;
697 return snoop_response_latency;
698}
699
700std::pair<MemCmd, Tick>
701CoherentXBar::forwardAtomic(PacketPtr pkt, PortID exclude_slave_port_id,
702 PortID source_master_port_id,
703 const std::vector<SlavePort*>& dests)
704{
705 // the packet may be changed on snoops, record the original
706 // command to enable us to restore it between snoops so that
707 // additional snoops can take place properly
708 MemCmd orig_cmd = pkt->cmd;
709 MemCmd snoop_response_cmd = MemCmd::InvalidCmd;
710 Tick snoop_response_latency = 0;
711
712 // snoops should only happen if the system isn't bypassing caches
713 assert(!system->bypassCaches());
714
715 unsigned fanout = 0;
716
717 for (const auto& p: dests) {
718 // we could have gotten this request from a snooping master
719 // (corresponding to our own slave port that is also in
720 // snoopPorts) and should not send it back to where it came
721 // from
722 if (exclude_slave_port_id != InvalidPortID &&
723 p->getId() == exclude_slave_port_id)
724 continue;
725
726 Tick latency = p->sendAtomicSnoop(pkt);
727 fanout++;
728
729 // in contrast to a functional access, we have to keep on
730 // going as all snoopers must be updated even if we get a
731 // response
732 if (!pkt->isResponse())
733 continue;
734
735 // response from snoop agent
736 assert(pkt->cmd != orig_cmd);
737 assert(pkt->memInhibitAsserted());
738 // should only happen once
739 assert(snoop_response_cmd == MemCmd::InvalidCmd);
740 // save response state
741 snoop_response_cmd = pkt->cmd;
742 snoop_response_latency = latency;
743
744 if (snoopFilter) {
745 // Handle responses by the snoopers and differentiate between
746 // responses to requests from above and snoops from below
747 if (source_master_port_id != InvalidPortID) {
748 // Getting a response for a snoop from below
749 assert(exclude_slave_port_id == InvalidPortID);
750 snoopFilter->updateSnoopForward(pkt, *p,
751 *masterPorts[source_master_port_id]);
752 } else {
753 // Getting a response for a request from above
754 assert(source_master_port_id == InvalidPortID);
755 snoopFilter->updateSnoopResponse(pkt, *p,
756 *slavePorts[exclude_slave_port_id]);
757 }
758 }
759 // restore original packet state for remaining snoopers
760 pkt->cmd = orig_cmd;
761 }
762
763 // Stats for fanout
764 snoopFanout.sample(fanout);
765
766 // the packet is restored as part of the loop and any potential
767 // snoop response is part of the returned pair
768 return std::make_pair(snoop_response_cmd, snoop_response_latency);
769}
770
771void
772CoherentXBar::recvFunctional(PacketPtr pkt, PortID slave_port_id)
773{
774 if (!pkt->isPrint()) {
775 // don't do DPRINTFs on PrintReq as it clutters up the output
776 DPRINTF(CoherentXBar,
777 "recvFunctional: packet src %s addr 0x%x cmd %s\n",
778 slavePorts[slave_port_id]->name(), pkt->getAddr(),
779 pkt->cmdString());
780 }
781
782 if (!system->bypassCaches()) {
783 // forward to all snoopers but the source
784 forwardFunctional(pkt, slave_port_id);
785 }
786
787 // there is no need to continue if the snooping has found what we
788 // were looking for and the packet is already a response
789 if (!pkt->isResponse()) {
790 PortID dest_id = findPort(pkt->getAddr());
791
792 masterPorts[dest_id]->sendFunctional(pkt);
793 }
794}
795
796void
797CoherentXBar::recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id)
798{
799 if (!pkt->isPrint()) {
800 // don't do DPRINTFs on PrintReq as it clutters up the output
801 DPRINTF(CoherentXBar,
802 "recvFunctionalSnoop: packet src %s addr 0x%x cmd %s\n",
803 masterPorts[master_port_id]->name(), pkt->getAddr(),
804 pkt->cmdString());
805 }
806
807 // forward to all snoopers
808 forwardFunctional(pkt, InvalidPortID);
809}
810
811void
812CoherentXBar::forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id)
813{
814 // snoops should only happen if the system isn't bypassing caches
815 assert(!system->bypassCaches());
816
817 for (const auto& p: snoopPorts) {
818 // we could have gotten this request from a snooping master
819 // (corresponding to our own slave port that is also in
820 // snoopPorts) and should not send it back to where it came
821 // from
822 if (exclude_slave_port_id == InvalidPortID ||
823 p->getId() != exclude_slave_port_id)
824 p->sendFunctionalSnoop(pkt);
825
826 // if we get a response we are done
827 if (pkt->isResponse()) {
828 break;
829 }
830 }
831}
832
833unsigned int
834CoherentXBar::drain(DrainManager *dm)
835{
836 // sum up the individual layers
837 unsigned int total = 0;
838 for (auto l: reqLayers)
839 total += l->drain(dm);
840 for (auto l: respLayers)
841 total += l->drain(dm);
842 for (auto l: snoopLayers)
843 total += l->drain(dm);
844 return total;
845}
846
847void
848CoherentXBar::regStats()
849{
850 // register the stats of the base class and our layers
851 BaseXBar::regStats();
852 for (auto l: reqLayers)
853 l->regStats();
854 for (auto l: respLayers)
855 l->regStats();
856 for (auto l: snoopLayers)
857 l->regStats();
858
859 snoops
860 .name(name() + ".snoops")
861 .desc("Total snoops (count)")
862 ;
863
864 snoopFanout
865 .init(0, snoopPorts.size(), 1)
866 .name(name() + ".snoop_fanout")
867 .desc("Request fanout histogram")
868 ;
869}
870
871CoherentXBar *
872CoherentXBarParams::create()
873{
874 return new CoherentXBar(this);
875}