xbar.cc revision 10719
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/Drain.hh" 54#include "debug/XBar.hh" 55#include "mem/xbar.hh" 56 57BaseXBar::BaseXBar(const BaseXBarParams *p) 58 : MemObject(p), 59 frontendLatency(p->frontend_latency), 60 forwardLatency(p->forward_latency), 61 responseLatency(p->response_latency), 62 width(p->width), 63 gotAddrRanges(p->port_default_connection_count + 64 p->port_master_connection_count, false), 65 gotAllAddrRanges(false), defaultPortID(InvalidPortID), 66 useDefaultRange(p->use_default_range) 67{} 68 69BaseXBar::~BaseXBar() 70{ 71 for (auto m: masterPorts) 72 delete m; 73 74 for (auto s: slavePorts) 75 delete s; 76} 77 78void 79BaseXBar::init() 80{ 81} 82 83BaseMasterPort & 84BaseXBar::getMasterPort(const std::string &if_name, PortID idx) 85{ 86 if (if_name == "master" && idx < masterPorts.size()) { 87 // the master port index translates directly to the vector position 88 return *masterPorts[idx]; 89 } else if (if_name == "default") { 90 return *masterPorts[defaultPortID]; 91 } else { 92 return MemObject::getMasterPort(if_name, idx); 93 } 94} 95 96BaseSlavePort & 97BaseXBar::getSlavePort(const std::string &if_name, PortID idx) 98{ 99 if (if_name == "slave" && idx < slavePorts.size()) { 100 // the slave port index translates directly to the vector position 101 return *slavePorts[idx]; 102 } else { 103 return MemObject::getSlavePort(if_name, idx); 104 } 105} 106 107void 108BaseXBar::calcPacketTiming(PacketPtr pkt, Tick header_delay) 109{ 110 // the crossbar will be called at a time that is not necessarily 111 // coinciding with its own clock, so start by determining how long 112 // until the next clock edge (could be zero) 113 Tick offset = clockEdge() - curTick(); 114 115 // the header delay depends on the path through the crossbar, and 116 // we therefore rely on the caller to provide the actual 117 // value 118 pkt->headerDelay += offset + header_delay; 119 120 // note that we add the header delay to the existing value, and 121 // align it to the crossbar clock 122 123 // do a quick sanity check to ensure the timings are not being 124 // ignored, note that this specific value may cause problems for 125 // slower interconnects 126 panic_if(pkt->headerDelay > SimClock::Int::us, 127 "Encountered header delay exceeding 1 us\n"); 128 129 if (pkt->hasData()) { 130 // the payloadDelay takes into account the relative time to 131 // deliver the payload of the packet, after the header delay, 132 // we take the maximum since the payload delay could already 133 // be longer than what this parcitular crossbar enforces. 134 pkt->payloadDelay = std::max<Tick>(pkt->payloadDelay, 135 divCeil(pkt->getSize(), width) * 136 clockPeriod()); 137 } 138 139 // the payload delay is not paying for the clock offset as that is 140 // already done using the header delay, and the payload delay is 141 // also used to determine how long the crossbar layer is busy and 142 // thus regulates throughput 143} 144 145template <typename SrcType, typename DstType> 146BaseXBar::Layer<SrcType,DstType>::Layer(DstType& _port, BaseXBar& _xbar, 147 const std::string& _name) : 148 port(_port), xbar(_xbar), _name(_name), state(IDLE), drainManager(NULL), 149 waitingForPeer(NULL), releaseEvent(this) 150{ 151} 152 153template <typename SrcType, typename DstType> 154void BaseXBar::Layer<SrcType,DstType>::occupyLayer(Tick until) 155{ 156 // ensure the state is busy at this point, as the layer should 157 // transition from idle as soon as it has decided to forward the 158 // packet to prevent any follow-on calls to sendTiming seeing an 159 // unoccupied layer 160 assert(state == BUSY); 161 162 // until should never be 0 as express snoops never occupy the layer 163 assert(until != 0); 164 xbar.schedule(releaseEvent, until); 165 166 // account for the occupied ticks 167 occupancy += until - curTick(); 168 169 DPRINTF(BaseXBar, "The crossbar layer is now busy from tick %d to %d\n", 170 curTick(), until); 171} 172 173template <typename SrcType, typename DstType> 174bool 175BaseXBar::Layer<SrcType,DstType>::tryTiming(SrcType* src_port) 176{ 177 // if we are in the retry state, we will not see anything but the 178 // retrying port (or in the case of the snoop ports the snoop 179 // response port that mirrors the actual slave port) as we leave 180 // this state again in zero time if the peer does not immediately 181 // call the layer when receiving the retry 182 183 // first we see if the layer is busy, next we check if the 184 // destination port is already engaged in a transaction waiting 185 // for a retry from the peer 186 if (state == BUSY || waitingForPeer != NULL) { 187 // the port should not be waiting already 188 assert(std::find(waitingForLayer.begin(), waitingForLayer.end(), 189 src_port) == waitingForLayer.end()); 190 191 // put the port at the end of the retry list waiting for the 192 // layer to be freed up (and in the case of a busy peer, for 193 // that transaction to go through, and then the layer to free 194 // up) 195 waitingForLayer.push_back(src_port); 196 return false; 197 } 198 199 state = BUSY; 200 201 return true; 202} 203 204template <typename SrcType, typename DstType> 205void 206BaseXBar::Layer<SrcType,DstType>::succeededTiming(Tick busy_time) 207{ 208 // we should have gone from idle or retry to busy in the tryTiming 209 // test 210 assert(state == BUSY); 211 212 // occupy the layer accordingly 213 occupyLayer(busy_time); 214} 215 216template <typename SrcType, typename DstType> 217void 218BaseXBar::Layer<SrcType,DstType>::failedTiming(SrcType* src_port, 219 Tick busy_time) 220{ 221 // ensure no one got in between and tried to send something to 222 // this port 223 assert(waitingForPeer == NULL); 224 225 // if the source port is the current retrying one or not, we have 226 // failed in forwarding and should track that we are now waiting 227 // for the peer to send a retry 228 waitingForPeer = src_port; 229 230 // we should have gone from idle or retry to busy in the tryTiming 231 // test 232 assert(state == BUSY); 233 234 // occupy the bus accordingly 235 occupyLayer(busy_time); 236} 237 238template <typename SrcType, typename DstType> 239void 240BaseXBar::Layer<SrcType,DstType>::releaseLayer() 241{ 242 // releasing the bus means we should now be idle 243 assert(state == BUSY); 244 assert(!releaseEvent.scheduled()); 245 246 // update the state 247 state = IDLE; 248 249 // bus layer is now idle, so if someone is waiting we can retry 250 if (!waitingForLayer.empty()) { 251 // there is no point in sending a retry if someone is still 252 // waiting for the peer 253 if (waitingForPeer == NULL) 254 retryWaiting(); 255 } else if (waitingForPeer == NULL && drainManager) { 256 DPRINTF(Drain, "Crossbar done draining, signaling drain manager\n"); 257 //If we weren't able to drain before, do it now. 258 drainManager->signalDrainDone(); 259 // Clear the drain event once we're done with it. 260 drainManager = NULL; 261 } 262} 263 264template <typename SrcType, typename DstType> 265void 266BaseXBar::Layer<SrcType,DstType>::retryWaiting() 267{ 268 // this should never be called with no one waiting 269 assert(!waitingForLayer.empty()); 270 271 // we always go to retrying from idle 272 assert(state == IDLE); 273 274 // update the state 275 state = RETRY; 276 277 // set the retrying port to the front of the retry list and pop it 278 // off the list 279 SrcType* retryingPort = waitingForLayer.front(); 280 waitingForLayer.pop_front(); 281 282 // tell the port to retry, which in some cases ends up calling the 283 // layer again 284 sendRetry(retryingPort); 285 286 // If the layer is still in the retry state, sendTiming wasn't 287 // called in zero time (e.g. the cache does this when a writeback 288 // is squashed) 289 if (state == RETRY) { 290 // update the state to busy and reset the retrying port, we 291 // have done our bit and sent the retry 292 state = BUSY; 293 294 // occupy the crossbar layer until the next clock edge 295 occupyLayer(xbar.clockEdge()); 296 } 297} 298 299template <typename SrcType, typename DstType> 300void 301BaseXBar::Layer<SrcType,DstType>::recvRetry() 302{ 303 // we should never get a retry without having failed to forward 304 // something to this port 305 assert(waitingForPeer != NULL); 306 307 // add the port where the failed packet originated to the front of 308 // the waiting ports for the layer, this allows us to call retry 309 // on the port immediately if the crossbar layer is idle 310 waitingForLayer.push_front(waitingForPeer); 311 312 // we are no longer waiting for the peer 313 waitingForPeer = NULL; 314 315 // if the layer is idle, retry this port straight away, if we 316 // are busy, then simply let the port wait for its turn 317 if (state == IDLE) { 318 retryWaiting(); 319 } else { 320 assert(state == BUSY); 321 } 322} 323 324PortID 325BaseXBar::findPort(Addr addr) 326{ 327 // we should never see any address lookups before we've got the 328 // ranges of all connected slave modules 329 assert(gotAllAddrRanges); 330 331 // Check the cache 332 PortID dest_id = checkPortCache(addr); 333 if (dest_id != InvalidPortID) 334 return dest_id; 335 336 // Check the address map interval tree 337 auto i = portMap.find(addr); 338 if (i != portMap.end()) { 339 dest_id = i->second; 340 updatePortCache(dest_id, i->first); 341 return dest_id; 342 } 343 344 // Check if this matches the default range 345 if (useDefaultRange) { 346 if (defaultRange.contains(addr)) { 347 DPRINTF(AddrRanges, " found addr %#llx on default\n", 348 addr); 349 return defaultPortID; 350 } 351 } else if (defaultPortID != InvalidPortID) { 352 DPRINTF(AddrRanges, "Unable to find destination for addr %#llx, " 353 "will use default port\n", addr); 354 return defaultPortID; 355 } 356 357 // we should use the range for the default port and it did not 358 // match, or the default port is not set 359 fatal("Unable to find destination for addr %#llx on %s\n", addr, 360 name()); 361} 362 363/** Function called by the port when the crossbar is receiving a range change.*/ 364void 365BaseXBar::recvRangeChange(PortID master_port_id) 366{ 367 DPRINTF(AddrRanges, "Received range change from slave port %s\n", 368 masterPorts[master_port_id]->getSlavePort().name()); 369 370 // remember that we got a range from this master port and thus the 371 // connected slave module 372 gotAddrRanges[master_port_id] = true; 373 374 // update the global flag 375 if (!gotAllAddrRanges) { 376 // take a logical AND of all the ports and see if we got 377 // ranges from everyone 378 gotAllAddrRanges = true; 379 std::vector<bool>::const_iterator r = gotAddrRanges.begin(); 380 while (gotAllAddrRanges && r != gotAddrRanges.end()) { 381 gotAllAddrRanges &= *r++; 382 } 383 if (gotAllAddrRanges) 384 DPRINTF(AddrRanges, "Got address ranges from all slaves\n"); 385 } 386 387 // note that we could get the range from the default port at any 388 // point in time, and we cannot assume that the default range is 389 // set before the other ones are, so we do additional checks once 390 // all ranges are provided 391 if (master_port_id == defaultPortID) { 392 // only update if we are indeed checking ranges for the 393 // default port since the port might not have a valid range 394 // otherwise 395 if (useDefaultRange) { 396 AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges(); 397 398 if (ranges.size() != 1) 399 fatal("Crossbar %s may only have a single default range", 400 name()); 401 402 defaultRange = ranges.front(); 403 } 404 } else { 405 // the ports are allowed to update their address ranges 406 // dynamically, so remove any existing entries 407 if (gotAddrRanges[master_port_id]) { 408 for (auto p = portMap.begin(); p != portMap.end(); ) { 409 if (p->second == master_port_id) 410 // erasing invalidates the iterator, so advance it 411 // before the deletion takes place 412 portMap.erase(p++); 413 else 414 p++; 415 } 416 } 417 418 AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges(); 419 420 for (const auto& r: ranges) { 421 DPRINTF(AddrRanges, "Adding range %s for id %d\n", 422 r.to_string(), master_port_id); 423 if (portMap.insert(r, master_port_id) == portMap.end()) { 424 PortID conflict_id = portMap.find(r)->second; 425 fatal("%s has two ports responding within range %s:\n\t%s\n\t%s\n", 426 name(), 427 r.to_string(), 428 masterPorts[master_port_id]->getSlavePort().name(), 429 masterPorts[conflict_id]->getSlavePort().name()); 430 } 431 } 432 } 433 434 // if we have received ranges from all our neighbouring slave 435 // modules, go ahead and tell our connected master modules in 436 // turn, this effectively assumes a tree structure of the system 437 if (gotAllAddrRanges) { 438 DPRINTF(AddrRanges, "Aggregating address ranges\n"); 439 xbarRanges.clear(); 440 441 // start out with the default range 442 if (useDefaultRange) { 443 if (!gotAddrRanges[defaultPortID]) 444 fatal("Crossbar %s uses default range, but none provided", 445 name()); 446 447 xbarRanges.push_back(defaultRange); 448 DPRINTF(AddrRanges, "-- Adding default %s\n", 449 defaultRange.to_string()); 450 } 451 452 // merge all interleaved ranges and add any range that is not 453 // a subset of the default range 454 std::vector<AddrRange> intlv_ranges; 455 for (const auto& r: portMap) { 456 // if the range is interleaved then save it for now 457 if (r.first.interleaved()) { 458 // if we already got interleaved ranges that are not 459 // part of the same range, then first do a merge 460 // before we add the new one 461 if (!intlv_ranges.empty() && 462 !intlv_ranges.back().mergesWith(r.first)) { 463 DPRINTF(AddrRanges, "-- Merging range from %d ranges\n", 464 intlv_ranges.size()); 465 AddrRange merged_range(intlv_ranges); 466 // next decide if we keep the merged range or not 467 if (!(useDefaultRange && 468 merged_range.isSubset(defaultRange))) { 469 xbarRanges.push_back(merged_range); 470 DPRINTF(AddrRanges, "-- Adding merged range %s\n", 471 merged_range.to_string()); 472 } 473 intlv_ranges.clear(); 474 } 475 intlv_ranges.push_back(r.first); 476 } else { 477 // keep the current range if not a subset of the default 478 if (!(useDefaultRange && 479 r.first.isSubset(defaultRange))) { 480 xbarRanges.push_back(r.first); 481 DPRINTF(AddrRanges, "-- Adding range %s\n", 482 r.first.to_string()); 483 } 484 } 485 } 486 487 // if there is still interleaved ranges waiting to be merged, 488 // go ahead and do it 489 if (!intlv_ranges.empty()) { 490 DPRINTF(AddrRanges, "-- Merging range from %d ranges\n", 491 intlv_ranges.size()); 492 AddrRange merged_range(intlv_ranges); 493 if (!(useDefaultRange && merged_range.isSubset(defaultRange))) { 494 xbarRanges.push_back(merged_range); 495 DPRINTF(AddrRanges, "-- Adding merged range %s\n", 496 merged_range.to_string()); 497 } 498 } 499 500 // also check that no range partially overlaps with the 501 // default range, this has to be done after all ranges are set 502 // as there are no guarantees for when the default range is 503 // update with respect to the other ones 504 if (useDefaultRange) { 505 for (const auto& r: xbarRanges) { 506 // see if the new range is partially 507 // overlapping the default range 508 if (r.intersects(defaultRange) && 509 !r.isSubset(defaultRange)) 510 fatal("Range %s intersects the " \ 511 "default range of %s but is not a " \ 512 "subset\n", r.to_string(), name()); 513 } 514 } 515 516 // tell all our neighbouring master ports that our address 517 // ranges have changed 518 for (const auto& s: slavePorts) 519 s->sendRangeChange(); 520 } 521 522 clearPortCache(); 523} 524 525AddrRangeList 526BaseXBar::getAddrRanges() const 527{ 528 // we should never be asked without first having sent a range 529 // change, and the latter is only done once we have all the ranges 530 // of the connected devices 531 assert(gotAllAddrRanges); 532 533 // at the moment, this never happens, as there are no cycles in 534 // the range queries and no devices on the master side of a crossbar 535 // (CPU, cache, bridge etc) actually care about the ranges of the 536 // ports they are connected to 537 538 DPRINTF(AddrRanges, "Received address range request\n"); 539 540 return xbarRanges; 541} 542 543void 544BaseXBar::regStats() 545{ 546 using namespace Stats; 547 548 transDist 549 .init(MemCmd::NUM_MEM_CMDS) 550 .name(name() + ".trans_dist") 551 .desc("Transaction distribution") 552 .flags(nozero); 553 554 // get the string representation of the commands 555 for (int i = 0; i < MemCmd::NUM_MEM_CMDS; i++) { 556 MemCmd cmd(i); 557 const std::string &cstr = cmd.toString(); 558 transDist.subname(i, cstr); 559 } 560 561 pktCount 562 .init(slavePorts.size(), masterPorts.size()) 563 .name(name() + ".pkt_count") 564 .desc("Packet count per connected master and slave (bytes)") 565 .flags(total | nozero | nonan); 566 567 pktSize 568 .init(slavePorts.size(), masterPorts.size()) 569 .name(name() + ".pkt_size") 570 .desc("Cumulative packet size per connected master and slave (bytes)") 571 .flags(total | nozero | nonan); 572 573 // both the packet count and total size are two-dimensional 574 // vectors, indexed by slave port id and master port id, thus the 575 // neighbouring master and slave, they do not differentiate what 576 // came from the master and was forwarded to the slave (requests 577 // and snoop responses) and what came from the slave and was 578 // forwarded to the master (responses and snoop requests) 579 for (int i = 0; i < slavePorts.size(); i++) { 580 pktCount.subname(i, slavePorts[i]->getMasterPort().name()); 581 pktSize.subname(i, slavePorts[i]->getMasterPort().name()); 582 for (int j = 0; j < masterPorts.size(); j++) { 583 pktCount.ysubname(j, masterPorts[j]->getSlavePort().name()); 584 pktSize.ysubname(j, masterPorts[j]->getSlavePort().name()); 585 } 586 } 587} 588 589template <typename SrcType, typename DstType> 590unsigned int 591BaseXBar::Layer<SrcType,DstType>::drain(DrainManager *dm) 592{ 593 //We should check that we're not "doing" anything, and that noone is 594 //waiting. We might be idle but have someone waiting if the device we 595 //contacted for a retry didn't actually retry. 596 if (state != IDLE) { 597 DPRINTF(Drain, "Crossbar not drained\n"); 598 drainManager = dm; 599 return 1; 600 } 601 return 0; 602} 603 604template <typename SrcType, typename DstType> 605void 606BaseXBar::Layer<SrcType,DstType>::regStats() 607{ 608 using namespace Stats; 609 610 occupancy 611 .name(name() + ".occupancy") 612 .desc("Layer occupancy (ticks)") 613 .flags(nozero); 614 615 utilization 616 .name(name() + ".utilization") 617 .desc("Layer utilization (%)") 618 .precision(1) 619 .flags(nozero); 620 621 utilization = 100 * occupancy / simTicks; 622} 623 624/** 625 * Crossbar layer template instantiations. Could be removed with _impl.hh 626 * file, but since there are only two given options (MasterPort and 627 * SlavePort) it seems a bit excessive at this point. 628 */ 629template class BaseXBar::Layer<SlavePort,MasterPort>; 630template class BaseXBar::Layer<MasterPort,SlavePort>; 631