coherent_xbar.cc revision 10821:581fb2484bd6
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 // determine the source port based on the id 142 SlavePort *src_port = slavePorts[slave_port_id]; 143 144 // remember if the packet is an express snoop 145 bool is_express_snoop = pkt->isExpressSnoop(); 146 bool is_inhibited = pkt->memInhibitAsserted(); 147 // for normal requests, going downstream, the express snoop flag 148 // and the inhibited flag should always be the same 149 assert(is_express_snoop == is_inhibited); 150 151 // determine the destination based on the address 152 PortID master_port_id = findPort(pkt->getAddr()); 153 154 // test if the crossbar should be considered occupied for the current 155 // port, and exclude express snoops from the check 156 if (!is_express_snoop && !reqLayers[master_port_id]->tryTiming(src_port)) { 157 DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x BUSY\n", 158 src_port->name(), pkt->cmdString(), pkt->getAddr()); 159 return false; 160 } 161 162 DPRINTF(CoherentXBar, "recvTimingReq: src %s %s expr %d 0x%x\n", 163 src_port->name(), pkt->cmdString(), is_express_snoop, 164 pkt->getAddr()); 165 166 // store size and command as they might be modified when 167 // forwarding the packet 168 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; 169 unsigned int pkt_cmd = pkt->cmdToIndex(); 170 171 // store the old header delay so we can restore it if needed 172 Tick old_header_delay = pkt->headerDelay; 173 174 // a request sees the frontend and forward latency 175 Tick xbar_delay = (frontendLatency + forwardLatency) * clockPeriod(); 176 177 // set the packet header and payload delay 178 calcPacketTiming(pkt, xbar_delay); 179 180 // determine how long to be crossbar layer is busy 181 Tick packetFinishTime = clockEdge(Cycles(1)) + pkt->payloadDelay; 182 183 if (!system->bypassCaches()) { 184 // the packet is a memory-mapped request and should be 185 // broadcasted to our snoopers but the source 186 if (snoopFilter) { 187 // check with the snoop filter where to forward this packet 188 auto sf_res = snoopFilter->lookupRequest(pkt, *src_port); 189 // If SnoopFilter is enabled, the total time required by a packet 190 // to be delivered through the xbar has to be charged also with 191 // to lookup latency of the snoop filter (sf_res.second). 192 pkt->headerDelay += sf_res.second * clockPeriod(); 193 packetFinishTime += sf_res.second * clockPeriod(); 194 DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x"\ 195 " SF size: %i lat: %i\n", src_port->name(), 196 pkt->cmdString(), pkt->getAddr(), sf_res.first.size(), 197 sf_res.second); 198 forwardTiming(pkt, slave_port_id, sf_res.first); 199 } else { 200 forwardTiming(pkt, slave_port_id); 201 } 202 } 203 204 // remember if the packet will generate a snoop response 205 const bool expect_snoop_resp = !is_inhibited && pkt->memInhibitAsserted(); 206 const bool expect_response = pkt->needsResponse() && 207 !pkt->memInhibitAsserted(); 208 209 // Note: Cannot create a copy of the full packet, here. 210 MemCmd orig_cmd(pkt->cmd); 211 212 // since it is a normal request, attempt to send the packet 213 bool success = masterPorts[master_port_id]->sendTimingReq(pkt); 214 215 if (snoopFilter && !system->bypassCaches()) { 216 // The packet may already be overwritten by the sendTimingReq function. 217 // The snoop filter needs to see the original request *and* the return 218 // status of the send operation, so we need to recreate the original 219 // request. Atomic mode does not have the issue, as there the send 220 // operation and the response happen instantaneously and don't need two 221 // phase tracking. 222 MemCmd tmp_cmd(pkt->cmd); 223 pkt->cmd = orig_cmd; 224 // Let the snoop filter know about the success of the send operation 225 snoopFilter->updateRequest(pkt, *src_port, !success); 226 pkt->cmd = tmp_cmd; 227 } 228 229 // check if we were successful in sending the packet onwards 230 if (!success) { 231 // express snoops and inhibited packets should never be forced 232 // to retry 233 assert(!is_express_snoop); 234 assert(!pkt->memInhibitAsserted()); 235 236 // restore the header delay 237 pkt->headerDelay = old_header_delay; 238 239 DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x RETRY\n", 240 src_port->name(), pkt->cmdString(), pkt->getAddr()); 241 242 // update the layer state and schedule an idle event 243 reqLayers[master_port_id]->failedTiming(src_port, 244 clockEdge(Cycles(1))); 245 } else { 246 // express snoops currently bypass the crossbar state entirely 247 if (!is_express_snoop) { 248 // if this particular request will generate a snoop 249 // response 250 if (expect_snoop_resp) { 251 // we should never have an exsiting request outstanding 252 assert(outstandingSnoop.find(pkt->req) == 253 outstandingSnoop.end()); 254 outstandingSnoop.insert(pkt->req); 255 256 // basic sanity check on the outstanding snoops 257 panic_if(outstandingSnoop.size() > 512, 258 "Outstanding snoop requests exceeded 512\n"); 259 } 260 261 // remember where to route the normal response to 262 if (expect_response || expect_snoop_resp) { 263 assert(routeTo.find(pkt->req) == routeTo.end()); 264 routeTo[pkt->req] = slave_port_id; 265 266 panic_if(routeTo.size() > 512, 267 "Routing table exceeds 512 packets\n"); 268 } 269 270 // update the layer state and schedule an idle event 271 reqLayers[master_port_id]->succeededTiming(packetFinishTime); 272 } 273 274 // stats updates only consider packets that were successfully sent 275 pktCount[slave_port_id][master_port_id]++; 276 pktSize[slave_port_id][master_port_id] += pkt_size; 277 transDist[pkt_cmd]++; 278 279 if (is_express_snoop) 280 snoops++; 281 } 282 283 return success; 284} 285 286bool 287CoherentXBar::recvTimingResp(PacketPtr pkt, PortID master_port_id) 288{ 289 // determine the source port based on the id 290 MasterPort *src_port = masterPorts[master_port_id]; 291 292 // determine the destination 293 const auto route_lookup = routeTo.find(pkt->req); 294 assert(route_lookup != routeTo.end()); 295 const PortID slave_port_id = route_lookup->second; 296 assert(slave_port_id != InvalidPortID); 297 assert(slave_port_id < respLayers.size()); 298 299 // test if the crossbar should be considered occupied for the 300 // current port 301 if (!respLayers[slave_port_id]->tryTiming(src_port)) { 302 DPRINTF(CoherentXBar, "recvTimingResp: src %s %s 0x%x BUSY\n", 303 src_port->name(), pkt->cmdString(), pkt->getAddr()); 304 return false; 305 } 306 307 DPRINTF(CoherentXBar, "recvTimingResp: src %s %s 0x%x\n", 308 src_port->name(), pkt->cmdString(), pkt->getAddr()); 309 310 // store size and command as they might be modified when 311 // forwarding the packet 312 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; 313 unsigned int pkt_cmd = pkt->cmdToIndex(); 314 315 // a response sees the response latency 316 Tick xbar_delay = responseLatency * clockPeriod(); 317 318 // set the packet header and payload delay 319 calcPacketTiming(pkt, xbar_delay); 320 321 // determine how long to be crossbar layer is busy 322 Tick packetFinishTime = clockEdge(Cycles(1)) + pkt->payloadDelay; 323 324 if (snoopFilter && !system->bypassCaches()) { 325 // let the snoop filter inspect the response and update its state 326 snoopFilter->updateResponse(pkt, *slavePorts[slave_port_id]); 327 } 328 329 // send the packet through the destination slave port 330 bool success M5_VAR_USED = slavePorts[slave_port_id]->sendTimingResp(pkt); 331 332 // currently it is illegal to block responses... can lead to 333 // deadlock 334 assert(success); 335 336 // remove the request from the routing table 337 routeTo.erase(route_lookup); 338 339 respLayers[slave_port_id]->succeededTiming(packetFinishTime); 340 341 // stats updates 342 pktCount[slave_port_id][master_port_id]++; 343 pktSize[slave_port_id][master_port_id] += pkt_size; 344 transDist[pkt_cmd]++; 345 346 return true; 347} 348 349void 350CoherentXBar::recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id) 351{ 352 DPRINTF(CoherentXBar, "recvTimingSnoopReq: src %s %s 0x%x\n", 353 masterPorts[master_port_id]->name(), pkt->cmdString(), 354 pkt->getAddr()); 355 356 // update stats here as we know the forwarding will succeed 357 transDist[pkt->cmdToIndex()]++; 358 snoops++; 359 360 // we should only see express snoops from caches 361 assert(pkt->isExpressSnoop()); 362 363 // remeber if the packet is inhibited so we can see if it changes 364 const bool is_inhibited = pkt->memInhibitAsserted(); 365 366 if (snoopFilter) { 367 // let the Snoop Filter work its magic and guide probing 368 auto sf_res = snoopFilter->lookupSnoop(pkt); 369 // No timing here: packetFinishTime += sf_res.second * clockPeriod(); 370 DPRINTF(CoherentXBar, "recvTimingSnoopReq: src %s %s 0x%x"\ 371 " SF size: %i lat: %i\n", masterPorts[master_port_id]->name(), 372 pkt->cmdString(), pkt->getAddr(), sf_res.first.size(), 373 sf_res.second); 374 375 // forward to all snoopers 376 forwardTiming(pkt, InvalidPortID, sf_res.first); 377 } else { 378 forwardTiming(pkt, InvalidPortID); 379 } 380 381 // if we can expect a response, remember how to route it 382 if (!is_inhibited && pkt->memInhibitAsserted()) { 383 assert(routeTo.find(pkt->req) == routeTo.end()); 384 routeTo[pkt->req] = master_port_id; 385 } 386 387 // a snoop request came from a connected slave device (one of 388 // our master ports), and if it is not coming from the slave 389 // device responsible for the address range something is 390 // wrong, hence there is nothing further to do as the packet 391 // would be going back to where it came from 392 assert(master_port_id == findPort(pkt->getAddr())); 393} 394 395bool 396CoherentXBar::recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id) 397{ 398 // determine the source port based on the id 399 SlavePort* src_port = slavePorts[slave_port_id]; 400 401 // get the destination 402 const auto route_lookup = routeTo.find(pkt->req); 403 assert(route_lookup != routeTo.end()); 404 const PortID dest_port_id = route_lookup->second; 405 assert(dest_port_id != InvalidPortID); 406 407 // determine if the response is from a snoop request we 408 // created as the result of a normal request (in which case it 409 // should be in the outstandingSnoop), or if we merely forwarded 410 // someone else's snoop request 411 const bool forwardAsSnoop = outstandingSnoop.find(pkt->req) == 412 outstandingSnoop.end(); 413 414 // test if the crossbar should be considered occupied for the 415 // current port, note that the check is bypassed if the response 416 // is being passed on as a normal response since this is occupying 417 // the response layer rather than the snoop response layer 418 if (forwardAsSnoop) { 419 assert(dest_port_id < snoopLayers.size()); 420 if (!snoopLayers[dest_port_id]->tryTiming(src_port)) { 421 DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n", 422 src_port->name(), pkt->cmdString(), pkt->getAddr()); 423 return false; 424 } 425 } else { 426 // get the master port that mirrors this slave port internally 427 MasterPort* snoop_port = snoopRespPorts[slave_port_id]; 428 assert(dest_port_id < respLayers.size()); 429 if (!respLayers[dest_port_id]->tryTiming(snoop_port)) { 430 DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n", 431 snoop_port->name(), pkt->cmdString(), pkt->getAddr()); 432 return false; 433 } 434 } 435 436 DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x\n", 437 src_port->name(), pkt->cmdString(), pkt->getAddr()); 438 439 // store size and command as they might be modified when 440 // forwarding the packet 441 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; 442 unsigned int pkt_cmd = pkt->cmdToIndex(); 443 444 // responses are never express snoops 445 assert(!pkt->isExpressSnoop()); 446 447 // a snoop response sees the snoop response latency, and if it is 448 // forwarded as a normal response, the response latency 449 Tick xbar_delay = 450 (forwardAsSnoop ? snoopResponseLatency : responseLatency) * 451 clockPeriod(); 452 453 // set the packet header and payload delay 454 calcPacketTiming(pkt, xbar_delay); 455 456 // determine how long to be crossbar layer is busy 457 Tick packetFinishTime = clockEdge(Cycles(1)) + pkt->payloadDelay; 458 459 // forward it either as a snoop response or a normal response 460 if (forwardAsSnoop) { 461 // this is a snoop response to a snoop request we forwarded, 462 // e.g. coming from the L1 and going to the L2, and it should 463 // be forwarded as a snoop response 464 465 if (snoopFilter) { 466 // update the probe filter so that it can properly track the line 467 snoopFilter->updateSnoopForward(pkt, *slavePorts[slave_port_id], 468 *masterPorts[dest_port_id]); 469 } 470 471 bool success M5_VAR_USED = 472 masterPorts[dest_port_id]->sendTimingSnoopResp(pkt); 473 pktCount[slave_port_id][dest_port_id]++; 474 pktSize[slave_port_id][dest_port_id] += pkt_size; 475 assert(success); 476 477 snoopLayers[dest_port_id]->succeededTiming(packetFinishTime); 478 } else { 479 // we got a snoop response on one of our slave ports, 480 // i.e. from a coherent master connected to the crossbar, and 481 // since we created the snoop request as part of recvTiming, 482 // this should now be a normal response again 483 outstandingSnoop.erase(pkt->req); 484 485 // this is a snoop response from a coherent master, hence it 486 // should never go back to where the snoop response came from, 487 // but instead to where the original request came from 488 assert(slave_port_id != dest_port_id); 489 490 if (snoopFilter) { 491 // update the probe filter so that it can properly track the line 492 snoopFilter->updateSnoopResponse(pkt, *slavePorts[slave_port_id], 493 *slavePorts[dest_port_id]); 494 } 495 496 DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x"\ 497 " FWD RESP\n", src_port->name(), pkt->cmdString(), 498 pkt->getAddr()); 499 500 // as a normal response, it should go back to a master through 501 // one of our slave ports, at this point we are ignoring the 502 // fact that the response layer could be busy and do not touch 503 // its state 504 bool success M5_VAR_USED = 505 slavePorts[dest_port_id]->sendTimingResp(pkt); 506 507 // @todo Put the response in an internal FIFO and pass it on 508 // to the response layer from there 509 510 // currently it is illegal to block responses... can lead 511 // to deadlock 512 assert(success); 513 514 respLayers[dest_port_id]->succeededTiming(packetFinishTime); 515 } 516 517 // remove the request from the routing table 518 routeTo.erase(route_lookup); 519 520 // stats updates 521 transDist[pkt_cmd]++; 522 snoops++; 523 524 return true; 525} 526 527 528void 529CoherentXBar::forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id, 530 const std::vector<SlavePort*>& dests) 531{ 532 DPRINTF(CoherentXBar, "%s for %s address %x size %d\n", __func__, 533 pkt->cmdString(), pkt->getAddr(), pkt->getSize()); 534 535 // snoops should only happen if the system isn't bypassing caches 536 assert(!system->bypassCaches()); 537 538 unsigned fanout = 0; 539 540 for (const auto& p: dests) { 541 // we could have gotten this request from a snooping master 542 // (corresponding to our own slave port that is also in 543 // snoopPorts) and should not send it back to where it came 544 // from 545 if (exclude_slave_port_id == InvalidPortID || 546 p->getId() != exclude_slave_port_id) { 547 // cache is not allowed to refuse snoop 548 p->sendTimingSnoopReq(pkt); 549 fanout++; 550 } 551 } 552 553 // Stats for fanout of this forward operation 554 snoopFanout.sample(fanout); 555} 556 557void 558CoherentXBar::recvReqRetry(PortID master_port_id) 559{ 560 // responses and snoop responses never block on forwarding them, 561 // so the retry will always be coming from a port to which we 562 // tried to forward a request 563 reqLayers[master_port_id]->recvRetry(); 564} 565 566Tick 567CoherentXBar::recvAtomic(PacketPtr pkt, PortID slave_port_id) 568{ 569 DPRINTF(CoherentXBar, "recvAtomic: packet src %s addr 0x%x cmd %s\n", 570 slavePorts[slave_port_id]->name(), pkt->getAddr(), 571 pkt->cmdString()); 572 573 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; 574 unsigned int pkt_cmd = pkt->cmdToIndex(); 575 576 MemCmd snoop_response_cmd = MemCmd::InvalidCmd; 577 Tick snoop_response_latency = 0; 578 579 if (!system->bypassCaches()) { 580 // forward to all snoopers but the source 581 std::pair<MemCmd, Tick> snoop_result; 582 if (snoopFilter) { 583 // check with the snoop filter where to forward this packet 584 auto sf_res = 585 snoopFilter->lookupRequest(pkt, *slavePorts[slave_port_id]); 586 snoop_response_latency += sf_res.second * clockPeriod(); 587 DPRINTF(CoherentXBar, "%s: src %s %s 0x%x"\ 588 " SF size: %i lat: %i\n", __func__, 589 slavePorts[slave_port_id]->name(), pkt->cmdString(), 590 pkt->getAddr(), sf_res.first.size(), sf_res.second); 591 snoop_result = forwardAtomic(pkt, slave_port_id, InvalidPortID, 592 sf_res.first); 593 } else { 594 snoop_result = forwardAtomic(pkt, slave_port_id); 595 } 596 snoop_response_cmd = snoop_result.first; 597 snoop_response_latency += snoop_result.second; 598 } 599 600 // even if we had a snoop response, we must continue and also 601 // perform the actual request at the destination 602 PortID master_port_id = findPort(pkt->getAddr()); 603 604 // stats updates for the request 605 pktCount[slave_port_id][master_port_id]++; 606 pktSize[slave_port_id][master_port_id] += pkt_size; 607 transDist[pkt_cmd]++; 608 609 // forward the request to the appropriate destination 610 Tick response_latency = masterPorts[master_port_id]->sendAtomic(pkt); 611 612 // Lower levels have replied, tell the snoop filter 613 if (snoopFilter && !system->bypassCaches() && pkt->isResponse()) { 614 snoopFilter->updateResponse(pkt, *slavePorts[slave_port_id]); 615 } 616 617 // if we got a response from a snooper, restore it here 618 if (snoop_response_cmd != MemCmd::InvalidCmd) { 619 // no one else should have responded 620 assert(!pkt->isResponse()); 621 pkt->cmd = snoop_response_cmd; 622 response_latency = snoop_response_latency; 623 } 624 625 // add the response data 626 if (pkt->isResponse()) { 627 pkt_size = pkt->hasData() ? pkt->getSize() : 0; 628 pkt_cmd = pkt->cmdToIndex(); 629 630 // stats updates 631 pktCount[slave_port_id][master_port_id]++; 632 pktSize[slave_port_id][master_port_id] += pkt_size; 633 transDist[pkt_cmd]++; 634 } 635 636 // @todo: Not setting header time 637 pkt->payloadDelay = response_latency; 638 return response_latency; 639} 640 641Tick 642CoherentXBar::recvAtomicSnoop(PacketPtr pkt, PortID master_port_id) 643{ 644 DPRINTF(CoherentXBar, "recvAtomicSnoop: packet src %s addr 0x%x cmd %s\n", 645 masterPorts[master_port_id]->name(), pkt->getAddr(), 646 pkt->cmdString()); 647 648 // add the request snoop data 649 snoops++; 650 651 // forward to all snoopers 652 std::pair<MemCmd, Tick> snoop_result; 653 Tick snoop_response_latency = 0; 654 if (snoopFilter) { 655 auto sf_res = snoopFilter->lookupSnoop(pkt); 656 snoop_response_latency += sf_res.second * clockPeriod(); 657 DPRINTF(CoherentXBar, "%s: src %s %s 0x%x SF size: %i lat: %i\n", 658 __func__, masterPorts[master_port_id]->name(), pkt->cmdString(), 659 pkt->getAddr(), sf_res.first.size(), sf_res.second); 660 snoop_result = forwardAtomic(pkt, InvalidPortID, master_port_id, 661 sf_res.first); 662 } else { 663 snoop_result = forwardAtomic(pkt, InvalidPortID); 664 } 665 MemCmd snoop_response_cmd = snoop_result.first; 666 snoop_response_latency += snoop_result.second; 667 668 if (snoop_response_cmd != MemCmd::InvalidCmd) 669 pkt->cmd = snoop_response_cmd; 670 671 // add the response snoop data 672 if (pkt->isResponse()) { 673 snoops++; 674 } 675 676 // @todo: Not setting header time 677 pkt->payloadDelay = snoop_response_latency; 678 return snoop_response_latency; 679} 680 681std::pair<MemCmd, Tick> 682CoherentXBar::forwardAtomic(PacketPtr pkt, PortID exclude_slave_port_id, 683 PortID source_master_port_id, 684 const std::vector<SlavePort*>& dests) 685{ 686 // the packet may be changed on snoops, record the original 687 // command to enable us to restore it between snoops so that 688 // additional snoops can take place properly 689 MemCmd orig_cmd = pkt->cmd; 690 MemCmd snoop_response_cmd = MemCmd::InvalidCmd; 691 Tick snoop_response_latency = 0; 692 693 // snoops should only happen if the system isn't bypassing caches 694 assert(!system->bypassCaches()); 695 696 unsigned fanout = 0; 697 698 for (const auto& p: dests) { 699 // we could have gotten this request from a snooping master 700 // (corresponding to our own slave port that is also in 701 // snoopPorts) and should not send it back to where it came 702 // from 703 if (exclude_slave_port_id != InvalidPortID && 704 p->getId() == exclude_slave_port_id) 705 continue; 706 707 Tick latency = p->sendAtomicSnoop(pkt); 708 fanout++; 709 710 // in contrast to a functional access, we have to keep on 711 // going as all snoopers must be updated even if we get a 712 // response 713 if (!pkt->isResponse()) 714 continue; 715 716 // response from snoop agent 717 assert(pkt->cmd != orig_cmd); 718 assert(pkt->memInhibitAsserted()); 719 // should only happen once 720 assert(snoop_response_cmd == MemCmd::InvalidCmd); 721 // save response state 722 snoop_response_cmd = pkt->cmd; 723 snoop_response_latency = latency; 724 725 if (snoopFilter) { 726 // Handle responses by the snoopers and differentiate between 727 // responses to requests from above and snoops from below 728 if (source_master_port_id != InvalidPortID) { 729 // Getting a response for a snoop from below 730 assert(exclude_slave_port_id == InvalidPortID); 731 snoopFilter->updateSnoopForward(pkt, *p, 732 *masterPorts[source_master_port_id]); 733 } else { 734 // Getting a response for a request from above 735 assert(source_master_port_id == InvalidPortID); 736 snoopFilter->updateSnoopResponse(pkt, *p, 737 *slavePorts[exclude_slave_port_id]); 738 } 739 } 740 // restore original packet state for remaining snoopers 741 pkt->cmd = orig_cmd; 742 } 743 744 // Stats for fanout 745 snoopFanout.sample(fanout); 746 747 // the packet is restored as part of the loop and any potential 748 // snoop response is part of the returned pair 749 return std::make_pair(snoop_response_cmd, snoop_response_latency); 750} 751 752void 753CoherentXBar::recvFunctional(PacketPtr pkt, PortID slave_port_id) 754{ 755 if (!pkt->isPrint()) { 756 // don't do DPRINTFs on PrintReq as it clutters up the output 757 DPRINTF(CoherentXBar, 758 "recvFunctional: packet src %s addr 0x%x cmd %s\n", 759 slavePorts[slave_port_id]->name(), pkt->getAddr(), 760 pkt->cmdString()); 761 } 762 763 if (!system->bypassCaches()) { 764 // forward to all snoopers but the source 765 forwardFunctional(pkt, slave_port_id); 766 } 767 768 // there is no need to continue if the snooping has found what we 769 // were looking for and the packet is already a response 770 if (!pkt->isResponse()) { 771 PortID dest_id = findPort(pkt->getAddr()); 772 773 masterPorts[dest_id]->sendFunctional(pkt); 774 } 775} 776 777void 778CoherentXBar::recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id) 779{ 780 if (!pkt->isPrint()) { 781 // don't do DPRINTFs on PrintReq as it clutters up the output 782 DPRINTF(CoherentXBar, 783 "recvFunctionalSnoop: packet src %s addr 0x%x cmd %s\n", 784 masterPorts[master_port_id]->name(), pkt->getAddr(), 785 pkt->cmdString()); 786 } 787 788 // forward to all snoopers 789 forwardFunctional(pkt, InvalidPortID); 790} 791 792void 793CoherentXBar::forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id) 794{ 795 // snoops should only happen if the system isn't bypassing caches 796 assert(!system->bypassCaches()); 797 798 for (const auto& p: snoopPorts) { 799 // we could have gotten this request from a snooping master 800 // (corresponding to our own slave port that is also in 801 // snoopPorts) and should not send it back to where it came 802 // from 803 if (exclude_slave_port_id == InvalidPortID || 804 p->getId() != exclude_slave_port_id) 805 p->sendFunctionalSnoop(pkt); 806 807 // if we get a response we are done 808 if (pkt->isResponse()) { 809 break; 810 } 811 } 812} 813 814unsigned int 815CoherentXBar::drain(DrainManager *dm) 816{ 817 // sum up the individual layers 818 unsigned int total = 0; 819 for (auto l: reqLayers) 820 total += l->drain(dm); 821 for (auto l: respLayers) 822 total += l->drain(dm); 823 for (auto l: snoopLayers) 824 total += l->drain(dm); 825 return total; 826} 827 828void 829CoherentXBar::regStats() 830{ 831 // register the stats of the base class and our layers 832 BaseXBar::regStats(); 833 for (auto l: reqLayers) 834 l->regStats(); 835 for (auto l: respLayers) 836 l->regStats(); 837 for (auto l: snoopLayers) 838 l->regStats(); 839 840 snoops 841 .name(name() + ".snoops") 842 .desc("Total snoops (count)") 843 ; 844 845 snoopFanout 846 .init(0, snoopPorts.size(), 1) 847 .name(name() + ".snoop_fanout") 848 .desc("Request fanout histogram") 849 ; 850} 851 852CoherentXBar * 853CoherentXBarParams::create() 854{ 855 return new CoherentXBar(this); 856} 857