xbar.cc revision 13784
1/* 2 * Copyright (c) 2011-2015, 2018 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 "mem/xbar.hh" 51 52#include "base/logging.hh" 53#include "base/trace.hh" 54#include "debug/AddrRanges.hh" 55#include "debug/Drain.hh" 56#include "debug/XBar.hh" 57 58BaseXBar::BaseXBar(const BaseXBarParams *p) 59 : MemObject(p), 60 frontendLatency(p->frontend_latency), 61 forwardLatency(p->forward_latency), 62 responseLatency(p->response_latency), 63 width(p->width), 64 gotAddrRanges(p->port_default_connection_count + 65 p->port_master_connection_count, false), 66 gotAllAddrRanges(false), defaultPortID(InvalidPortID), 67 useDefaultRange(p->use_default_range) 68{} 69 70BaseXBar::~BaseXBar() 71{ 72 for (auto m: masterPorts) 73 delete m; 74 75 for (auto s: slavePorts) 76 delete s; 77} 78 79void 80BaseXBar::init() 81{ 82} 83 84Port & 85BaseXBar::getPort(const std::string &if_name, PortID idx) 86{ 87 if (if_name == "master" && idx < masterPorts.size()) { 88 // the master port index translates directly to the vector position 89 return *masterPorts[idx]; 90 } else if (if_name == "default") { 91 return *masterPorts[defaultPortID]; 92 } else if (if_name == "slave" && idx < slavePorts.size()) { 93 // the slave port index translates directly to the vector position 94 return *slavePorts[idx]; 95 } else { 96 return MemObject::getPort(if_name, idx); 97 } 98} 99 100void 101BaseXBar::calcPacketTiming(PacketPtr pkt, Tick header_delay) 102{ 103 // the crossbar will be called at a time that is not necessarily 104 // coinciding with its own clock, so start by determining how long 105 // until the next clock edge (could be zero) 106 Tick offset = clockEdge() - curTick(); 107 108 // the header delay depends on the path through the crossbar, and 109 // we therefore rely on the caller to provide the actual 110 // value 111 pkt->headerDelay += offset + header_delay; 112 113 // note that we add the header delay to the existing value, and 114 // align it to the crossbar clock 115 116 // do a quick sanity check to ensure the timings are not being 117 // ignored, note that this specific value may cause problems for 118 // slower interconnects 119 panic_if(pkt->headerDelay > SimClock::Int::us, 120 "Encountered header delay exceeding 1 us\n"); 121 122 if (pkt->hasData()) { 123 // the payloadDelay takes into account the relative time to 124 // deliver the payload of the packet, after the header delay, 125 // we take the maximum since the payload delay could already 126 // be longer than what this parcitular crossbar enforces. 127 pkt->payloadDelay = std::max<Tick>(pkt->payloadDelay, 128 divCeil(pkt->getSize(), width) * 129 clockPeriod()); 130 } 131 132 // the payload delay is not paying for the clock offset as that is 133 // already done using the header delay, and the payload delay is 134 // also used to determine how long the crossbar layer is busy and 135 // thus regulates throughput 136} 137 138template <typename SrcType, typename DstType> 139BaseXBar::Layer<SrcType,DstType>::Layer(DstType& _port, BaseXBar& _xbar, 140 const std::string& _name) : 141 port(_port), xbar(_xbar), _name(_name), state(IDLE), 142 waitingForPeer(NULL), releaseEvent([this]{ releaseLayer(); }, name()) 143{ 144} 145 146template <typename SrcType, typename DstType> 147void BaseXBar::Layer<SrcType,DstType>::occupyLayer(Tick until) 148{ 149 // ensure the state is busy at this point, as the layer should 150 // transition from idle as soon as it has decided to forward the 151 // packet to prevent any follow-on calls to sendTiming seeing an 152 // unoccupied layer 153 assert(state == BUSY); 154 155 // until should never be 0 as express snoops never occupy the layer 156 assert(until != 0); 157 xbar.schedule(releaseEvent, until); 158 159 // account for the occupied ticks 160 occupancy += until - curTick(); 161 162 DPRINTF(BaseXBar, "The crossbar layer is now busy from tick %d to %d\n", 163 curTick(), until); 164} 165 166template <typename SrcType, typename DstType> 167bool 168BaseXBar::Layer<SrcType,DstType>::tryTiming(SrcType* src_port) 169{ 170 // if we are in the retry state, we will not see anything but the 171 // retrying port (or in the case of the snoop ports the snoop 172 // response port that mirrors the actual slave port) as we leave 173 // this state again in zero time if the peer does not immediately 174 // call the layer when receiving the retry 175 176 // first we see if the layer is busy, next we check if the 177 // destination port is already engaged in a transaction waiting 178 // for a retry from the peer 179 if (state == BUSY || waitingForPeer != NULL) { 180 // the port should not be waiting already 181 assert(std::find(waitingForLayer.begin(), waitingForLayer.end(), 182 src_port) == waitingForLayer.end()); 183 184 // put the port at the end of the retry list waiting for the 185 // layer to be freed up (and in the case of a busy peer, for 186 // that transaction to go through, and then the layer to free 187 // up) 188 waitingForLayer.push_back(src_port); 189 return false; 190 } 191 192 state = BUSY; 193 194 return true; 195} 196 197template <typename SrcType, typename DstType> 198void 199BaseXBar::Layer<SrcType,DstType>::succeededTiming(Tick busy_time) 200{ 201 // we should have gone from idle or retry to busy in the tryTiming 202 // test 203 assert(state == BUSY); 204 205 // occupy the layer accordingly 206 occupyLayer(busy_time); 207} 208 209template <typename SrcType, typename DstType> 210void 211BaseXBar::Layer<SrcType,DstType>::failedTiming(SrcType* src_port, 212 Tick busy_time) 213{ 214 // ensure no one got in between and tried to send something to 215 // this port 216 assert(waitingForPeer == NULL); 217 218 // if the source port is the current retrying one or not, we have 219 // failed in forwarding and should track that we are now waiting 220 // for the peer to send a retry 221 waitingForPeer = src_port; 222 223 // we should have gone from idle or retry to busy in the tryTiming 224 // test 225 assert(state == BUSY); 226 227 // occupy the bus accordingly 228 occupyLayer(busy_time); 229} 230 231template <typename SrcType, typename DstType> 232void 233BaseXBar::Layer<SrcType,DstType>::releaseLayer() 234{ 235 // releasing the bus means we should now be idle 236 assert(state == BUSY); 237 assert(!releaseEvent.scheduled()); 238 239 // update the state 240 state = IDLE; 241 242 // bus layer is now idle, so if someone is waiting we can retry 243 if (!waitingForLayer.empty()) { 244 // there is no point in sending a retry if someone is still 245 // waiting for the peer 246 if (waitingForPeer == NULL) 247 retryWaiting(); 248 } else if (waitingForPeer == NULL && drainState() == DrainState::Draining) { 249 DPRINTF(Drain, "Crossbar done draining, signaling drain manager\n"); 250 //If we weren't able to drain before, do it now. 251 signalDrainDone(); 252 } 253} 254 255template <typename SrcType, typename DstType> 256void 257BaseXBar::Layer<SrcType,DstType>::retryWaiting() 258{ 259 // this should never be called with no one waiting 260 assert(!waitingForLayer.empty()); 261 262 // we always go to retrying from idle 263 assert(state == IDLE); 264 265 // update the state 266 state = RETRY; 267 268 // set the retrying port to the front of the retry list and pop it 269 // off the list 270 SrcType* retryingPort = waitingForLayer.front(); 271 waitingForLayer.pop_front(); 272 273 // tell the port to retry, which in some cases ends up calling the 274 // layer again 275 sendRetry(retryingPort); 276 277 // If the layer is still in the retry state, sendTiming wasn't 278 // called in zero time (e.g. the cache does this when a writeback 279 // is squashed) 280 if (state == RETRY) { 281 // update the state to busy and reset the retrying port, we 282 // have done our bit and sent the retry 283 state = BUSY; 284 285 // occupy the crossbar layer until the next clock edge 286 occupyLayer(xbar.clockEdge()); 287 } 288} 289 290template <typename SrcType, typename DstType> 291void 292BaseXBar::Layer<SrcType,DstType>::recvRetry() 293{ 294 // we should never get a retry without having failed to forward 295 // something to this port 296 assert(waitingForPeer != NULL); 297 298 // add the port where the failed packet originated to the front of 299 // the waiting ports for the layer, this allows us to call retry 300 // on the port immediately if the crossbar layer is idle 301 waitingForLayer.push_front(waitingForPeer); 302 303 // we are no longer waiting for the peer 304 waitingForPeer = NULL; 305 306 // if the layer is idle, retry this port straight away, if we 307 // are busy, then simply let the port wait for its turn 308 if (state == IDLE) { 309 retryWaiting(); 310 } else { 311 assert(state == BUSY); 312 } 313} 314 315PortID 316BaseXBar::findPort(AddrRange addr_range) 317{ 318 // we should never see any address lookups before we've got the 319 // ranges of all connected slave modules 320 assert(gotAllAddrRanges); 321 322 // Check the address map interval tree 323 auto i = portMap.contains(addr_range); 324 if (i != portMap.end()) { 325 return i->second; 326 } 327 328 // Check if this matches the default range 329 if (useDefaultRange) { 330 if (addr_range.isSubset(defaultRange)) { 331 DPRINTF(AddrRanges, " found addr %s on default\n", 332 addr_range.to_string()); 333 return defaultPortID; 334 } 335 } else if (defaultPortID != InvalidPortID) { 336 DPRINTF(AddrRanges, "Unable to find destination for %s, " 337 "will use default port\n", addr_range.to_string()); 338 return defaultPortID; 339 } 340 341 // we should use the range for the default port and it did not 342 // match, or the default port is not set 343 fatal("Unable to find destination for %s on %s\n", addr_range.to_string(), 344 name()); 345} 346 347/** Function called by the port when the crossbar is receiving a range change.*/ 348void 349BaseXBar::recvRangeChange(PortID master_port_id) 350{ 351 DPRINTF(AddrRanges, "Received range change from slave port %s\n", 352 masterPorts[master_port_id]->getSlavePort().name()); 353 354 // remember that we got a range from this master port and thus the 355 // connected slave module 356 gotAddrRanges[master_port_id] = true; 357 358 // update the global flag 359 if (!gotAllAddrRanges) { 360 // take a logical AND of all the ports and see if we got 361 // ranges from everyone 362 gotAllAddrRanges = true; 363 std::vector<bool>::const_iterator r = gotAddrRanges.begin(); 364 while (gotAllAddrRanges && r != gotAddrRanges.end()) { 365 gotAllAddrRanges &= *r++; 366 } 367 if (gotAllAddrRanges) 368 DPRINTF(AddrRanges, "Got address ranges from all slaves\n"); 369 } 370 371 // note that we could get the range from the default port at any 372 // point in time, and we cannot assume that the default range is 373 // set before the other ones are, so we do additional checks once 374 // all ranges are provided 375 if (master_port_id == defaultPortID) { 376 // only update if we are indeed checking ranges for the 377 // default port since the port might not have a valid range 378 // otherwise 379 if (useDefaultRange) { 380 AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges(); 381 382 if (ranges.size() != 1) 383 fatal("Crossbar %s may only have a single default range", 384 name()); 385 386 defaultRange = ranges.front(); 387 } 388 } else { 389 // the ports are allowed to update their address ranges 390 // dynamically, so remove any existing entries 391 if (gotAddrRanges[master_port_id]) { 392 for (auto p = portMap.begin(); p != portMap.end(); ) { 393 if (p->second == master_port_id) 394 // erasing invalidates the iterator, so advance it 395 // before the deletion takes place 396 portMap.erase(p++); 397 else 398 p++; 399 } 400 } 401 402 AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges(); 403 404 for (const auto& r: ranges) { 405 DPRINTF(AddrRanges, "Adding range %s for id %d\n", 406 r.to_string(), master_port_id); 407 if (portMap.insert(r, master_port_id) == portMap.end()) { 408 PortID conflict_id = portMap.intersects(r)->second; 409 fatal("%s has two ports responding within range " 410 "%s:\n\t%s\n\t%s\n", 411 name(), 412 r.to_string(), 413 masterPorts[master_port_id]->getSlavePort().name(), 414 masterPorts[conflict_id]->getSlavePort().name()); 415 } 416 } 417 } 418 419 // if we have received ranges from all our neighbouring slave 420 // modules, go ahead and tell our connected master modules in 421 // turn, this effectively assumes a tree structure of the system 422 if (gotAllAddrRanges) { 423 DPRINTF(AddrRanges, "Aggregating address ranges\n"); 424 xbarRanges.clear(); 425 426 // start out with the default range 427 if (useDefaultRange) { 428 if (!gotAddrRanges[defaultPortID]) 429 fatal("Crossbar %s uses default range, but none provided", 430 name()); 431 432 xbarRanges.push_back(defaultRange); 433 DPRINTF(AddrRanges, "-- Adding default %s\n", 434 defaultRange.to_string()); 435 } 436 437 // merge all interleaved ranges and add any range that is not 438 // a subset of the default range 439 std::vector<AddrRange> intlv_ranges; 440 for (const auto& r: portMap) { 441 // if the range is interleaved then save it for now 442 if (r.first.interleaved()) { 443 // if we already got interleaved ranges that are not 444 // part of the same range, then first do a merge 445 // before we add the new one 446 if (!intlv_ranges.empty() && 447 !intlv_ranges.back().mergesWith(r.first)) { 448 DPRINTF(AddrRanges, "-- Merging range from %d ranges\n", 449 intlv_ranges.size()); 450 AddrRange merged_range(intlv_ranges); 451 // next decide if we keep the merged range or not 452 if (!(useDefaultRange && 453 merged_range.isSubset(defaultRange))) { 454 xbarRanges.push_back(merged_range); 455 DPRINTF(AddrRanges, "-- Adding merged range %s\n", 456 merged_range.to_string()); 457 } 458 intlv_ranges.clear(); 459 } 460 intlv_ranges.push_back(r.first); 461 } else { 462 // keep the current range if not a subset of the default 463 if (!(useDefaultRange && 464 r.first.isSubset(defaultRange))) { 465 xbarRanges.push_back(r.first); 466 DPRINTF(AddrRanges, "-- Adding range %s\n", 467 r.first.to_string()); 468 } 469 } 470 } 471 472 // if there is still interleaved ranges waiting to be merged, 473 // go ahead and do it 474 if (!intlv_ranges.empty()) { 475 DPRINTF(AddrRanges, "-- Merging range from %d ranges\n", 476 intlv_ranges.size()); 477 AddrRange merged_range(intlv_ranges); 478 if (!(useDefaultRange && merged_range.isSubset(defaultRange))) { 479 xbarRanges.push_back(merged_range); 480 DPRINTF(AddrRanges, "-- Adding merged range %s\n", 481 merged_range.to_string()); 482 } 483 } 484 485 // also check that no range partially intersects with the 486 // default range, this has to be done after all ranges are set 487 // as there are no guarantees for when the default range is 488 // update with respect to the other ones 489 if (useDefaultRange) { 490 for (const auto& r: xbarRanges) { 491 // see if the new range is partially 492 // overlapping the default range 493 if (r.intersects(defaultRange) && 494 !r.isSubset(defaultRange)) 495 fatal("Range %s intersects the " \ 496 "default range of %s but is not a " \ 497 "subset\n", r.to_string(), name()); 498 } 499 } 500 501 // tell all our neighbouring master ports that our address 502 // ranges have changed 503 for (const auto& s: slavePorts) 504 s->sendRangeChange(); 505 } 506} 507 508AddrRangeList 509BaseXBar::getAddrRanges() const 510{ 511 // we should never be asked without first having sent a range 512 // change, and the latter is only done once we have all the ranges 513 // of the connected devices 514 assert(gotAllAddrRanges); 515 516 // at the moment, this never happens, as there are no cycles in 517 // the range queries and no devices on the master side of a crossbar 518 // (CPU, cache, bridge etc) actually care about the ranges of the 519 // ports they are connected to 520 521 DPRINTF(AddrRanges, "Received address range request\n"); 522 523 return xbarRanges; 524} 525 526void 527BaseXBar::regStats() 528{ 529 ClockedObject::regStats(); 530 531 using namespace Stats; 532 533 transDist 534 .init(MemCmd::NUM_MEM_CMDS) 535 .name(name() + ".trans_dist") 536 .desc("Transaction distribution") 537 .flags(nozero); 538 539 // get the string representation of the commands 540 for (int i = 0; i < MemCmd::NUM_MEM_CMDS; i++) { 541 MemCmd cmd(i); 542 const std::string &cstr = cmd.toString(); 543 transDist.subname(i, cstr); 544 } 545 546 pktCount 547 .init(slavePorts.size(), masterPorts.size()) 548 .name(name() + ".pkt_count") 549 .desc("Packet count per connected master and slave (bytes)") 550 .flags(total | nozero | nonan); 551 552 pktSize 553 .init(slavePorts.size(), masterPorts.size()) 554 .name(name() + ".pkt_size") 555 .desc("Cumulative packet size per connected master and slave (bytes)") 556 .flags(total | nozero | nonan); 557 558 // both the packet count and total size are two-dimensional 559 // vectors, indexed by slave port id and master port id, thus the 560 // neighbouring master and slave, they do not differentiate what 561 // came from the master and was forwarded to the slave (requests 562 // and snoop responses) and what came from the slave and was 563 // forwarded to the master (responses and snoop requests) 564 for (int i = 0; i < slavePorts.size(); i++) { 565 pktCount.subname(i, slavePorts[i]->getMasterPort().name()); 566 pktSize.subname(i, slavePorts[i]->getMasterPort().name()); 567 for (int j = 0; j < masterPorts.size(); j++) { 568 pktCount.ysubname(j, masterPorts[j]->getSlavePort().name()); 569 pktSize.ysubname(j, masterPorts[j]->getSlavePort().name()); 570 } 571 } 572} 573 574template <typename SrcType, typename DstType> 575DrainState 576BaseXBar::Layer<SrcType,DstType>::drain() 577{ 578 //We should check that we're not "doing" anything, and that noone is 579 //waiting. We might be idle but have someone waiting if the device we 580 //contacted for a retry didn't actually retry. 581 if (state != IDLE) { 582 DPRINTF(Drain, "Crossbar not drained\n"); 583 return DrainState::Draining; 584 } else { 585 return DrainState::Drained; 586 } 587} 588 589template <typename SrcType, typename DstType> 590void 591BaseXBar::Layer<SrcType,DstType>::regStats() 592{ 593 using namespace Stats; 594 595 occupancy 596 .name(name() + ".occupancy") 597 .desc("Layer occupancy (ticks)") 598 .flags(nozero); 599 600 utilization 601 .name(name() + ".utilization") 602 .desc("Layer utilization (%)") 603 .precision(1) 604 .flags(nozero); 605 606 utilization = 100 * occupancy / simTicks; 607} 608 609/** 610 * Crossbar layer template instantiations. Could be removed with _impl.hh 611 * file, but since there are only two given options (MasterPort and 612 * SlavePort) it seems a bit excessive at this point. 613 */ 614template class BaseXBar::Layer<SlavePort,MasterPort>; 615template class BaseXBar::Layer<MasterPort,SlavePort>; 616