1/* 2 * Copyright (c) 2011-2013 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 * Copyright (c) 2015 The University of Bologna 16 * All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions are 20 * met: redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer; 22 * redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution; 25 * neither the name of the copyright holders nor the names of its 26 * contributors may be used to endorse or promote products derived from 27 * this software without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 40 * 41 * Authors: Ali Saidi 42 * Steve Reinhardt 43 * Andreas Hansson 44 * Erfan Azarkhish 45 */ 46 47/** 48 * @file 49 * Implementation of the SerialLink Class, modeling Hybrid-Memory-Cube's 50 * serial interface. 51 */ 52 53#include "mem/serial_link.hh" 54 55#include "base/trace.hh" 56#include "debug/SerialLink.hh" 57#include "params/SerialLink.hh" 58 |
59SerialLink::SerialLinkSlavePort::SerialLinkSlavePort(const std::string& _name, 60 SerialLink& _serial_link, 61 SerialLinkMasterPort& _masterPort, 62 Cycles _delay, int _resp_limit, 63 const std::vector<AddrRange>& 64 _ranges) 65 : SlavePort(_name, &_serial_link), serial_link(_serial_link), 66 masterPort(_masterPort), delay(_delay), 67 ranges(_ranges.begin(), _ranges.end()), 68 outstandingResponses(0), retryReq(false), 69 respQueueLimit(_resp_limit), sendEvent(*this) 70{ 71} 72 73SerialLink::SerialLinkMasterPort::SerialLinkMasterPort(const std::string& 74 _name, SerialLink& _serial_link, 75 SerialLinkSlavePort& _slavePort, 76 Cycles _delay, int _req_limit) 77 : MasterPort(_name, &_serial_link), serial_link(_serial_link), 78 slavePort(_slavePort), delay(_delay), reqQueueLimit(_req_limit), 79 sendEvent(*this) 80{ 81} 82 83SerialLink::SerialLink(SerialLinkParams *p) 84 : MemObject(p), 85 slavePort(p->name + ".slave", *this, masterPort, 86 ticksToCycles(p->delay), p->resp_size, p->ranges), 87 masterPort(p->name + ".master", *this, slavePort, 88 ticksToCycles(p->delay), p->req_size), 89 num_lanes(p->num_lanes), 90 link_speed(p->link_speed) 91 92{ 93} 94 95BaseMasterPort& 96SerialLink::getMasterPort(const std::string &if_name, PortID idx) 97{ 98 if (if_name == "master") 99 return masterPort; 100 else 101 // pass it along to our super class 102 return MemObject::getMasterPort(if_name, idx); 103} 104 105BaseSlavePort& 106SerialLink::getSlavePort(const std::string &if_name, PortID idx) 107{ 108 if (if_name == "slave") 109 return slavePort; 110 else 111 // pass it along to our super class 112 return MemObject::getSlavePort(if_name, idx); 113} 114 115void 116SerialLink::init() 117{ 118 // make sure both sides are connected and have the same block size 119 if (!slavePort.isConnected() || !masterPort.isConnected()) 120 fatal("Both ports of a serial_link must be connected.\n"); 121 122 // notify the master side of our address ranges 123 slavePort.sendRangeChange(); 124} 125 126bool 127SerialLink::SerialLinkSlavePort::respQueueFull() const 128{ 129 return outstandingResponses == respQueueLimit; 130} 131 132bool 133SerialLink::SerialLinkMasterPort::reqQueueFull() const 134{ 135 return transmitList.size() == reqQueueLimit; 136} 137 138bool 139SerialLink::SerialLinkMasterPort::recvTimingResp(PacketPtr pkt) 140{ 141 // all checks are done when the request is accepted on the slave 142 // side, so we are guaranteed to have space for the response 143 DPRINTF(SerialLink, "recvTimingResp: %s addr 0x%x\n", 144 pkt->cmdString(), pkt->getAddr()); 145 146 DPRINTF(SerialLink, "Request queue size: %d\n", transmitList.size()); 147 148 // @todo: We need to pay for this and not just zero it out 149 pkt->headerDelay = pkt->payloadDelay = 0; 150 151 // This is similar to what happens for the request packets: 152 // The serializer will start serialization as soon as it receives the 153 // first flit, but the deserializer (at the host side in this case), will 154 // have to wait to receive the whole packet. So we only account for the 155 // deserialization latency. 156 Cycles cycles = delay; 157 cycles += Cycles(divCeil(pkt->getSize() * 8, serial_link.num_lanes 158 * serial_link.link_speed)); 159 Tick t = serial_link.clockEdge(cycles); 160 161 //@todo: If the processor sends two uncached requests towards HMC and the 162 // second one is smaller than the first one. It may happen that the second 163 // one crosses this link faster than the first one (because the packet 164 // waits in the link based on its size). This can reorder the received 165 // response. 166 slavePort.schedTimingResp(pkt, t); 167 168 return true; 169} 170 171bool 172SerialLink::SerialLinkSlavePort::recvTimingReq(PacketPtr pkt) 173{ 174 DPRINTF(SerialLink, "recvTimingReq: %s addr 0x%x\n", 175 pkt->cmdString(), pkt->getAddr()); 176 177 // we should not see a timing request if we are already in a retry 178 assert(!retryReq); 179 180 DPRINTF(SerialLink, "Response queue size: %d outresp: %d\n", 181 transmitList.size(), outstandingResponses); 182 183 // if the request queue is full then there is no hope 184 if (masterPort.reqQueueFull()) { 185 DPRINTF(SerialLink, "Request queue full\n"); 186 retryReq = true; 187 } else if ( !retryReq ) { 188 // look at the response queue if we expect to see a response 189 bool expects_response = pkt->needsResponse() && 190 !pkt->cacheResponding(); 191 if (expects_response) { 192 if (respQueueFull()) { 193 DPRINTF(SerialLink, "Response queue full\n"); 194 retryReq = true; 195 } else { 196 // ok to send the request with space for the response 197 DPRINTF(SerialLink, "Reserving space for response\n"); 198 assert(outstandingResponses != respQueueLimit); 199 ++outstandingResponses; 200 201 // no need to set retryReq to false as this is already the 202 // case 203 } 204 } 205 206 if (!retryReq) { 207 // @todo: We need to pay for this and not just zero it out 208 pkt->headerDelay = pkt->payloadDelay = 0; 209 210 // We assume that the serializer component at the transmitter side 211 // does not need to receive the whole packet to start the 212 // serialization (this assumption is consistent with the HMC 213 // standard). But the deserializer waits for the complete packet 214 // to check its integrity first. So everytime a packet crosses a 215 // serial link, we should account for its deserialization latency 216 // only. 217 Cycles cycles = delay; 218 cycles += Cycles(divCeil(pkt->getSize() * 8, 219 serial_link.num_lanes * serial_link.link_speed)); 220 Tick t = serial_link.clockEdge(cycles); 221 222 //@todo: If the processor sends two uncached requests towards HMC 223 // and the second one is smaller than the first one. It may happen 224 // that the second one crosses this link faster than the first one 225 // (because the packet waits in the link based on its size). 226 // This can reorder the received response. 227 masterPort.schedTimingReq(pkt, t); 228 } 229 } 230 231 // remember that we are now stalling a packet and that we have to 232 // tell the sending master to retry once space becomes available, 233 // we make no distinction whether the stalling is due to the 234 // request queue or response queue being full 235 return !retryReq; 236} 237 238void 239SerialLink::SerialLinkSlavePort::retryStalledReq() 240{ 241 if (retryReq) { 242 DPRINTF(SerialLink, "Request waiting for retry, now retrying\n"); 243 retryReq = false; 244 sendRetryReq(); 245 } 246} 247 248void 249SerialLink::SerialLinkMasterPort::schedTimingReq(PacketPtr pkt, Tick when) 250{ 251 // If we're about to put this packet at the head of the queue, we 252 // need to schedule an event to do the transmit. Otherwise there 253 // should already be an event scheduled for sending the head 254 // packet. 255 if (transmitList.empty()) { 256 serial_link.schedule(sendEvent, when); 257 } 258 259 assert(transmitList.size() != reqQueueLimit); 260 261 transmitList.emplace_back(DeferredPacket(pkt, when)); 262} 263 264 265void 266SerialLink::SerialLinkSlavePort::schedTimingResp(PacketPtr pkt, Tick when) 267{ 268 // If we're about to put this packet at the head of the queue, we 269 // need to schedule an event to do the transmit. Otherwise there 270 // should already be an event scheduled for sending the head 271 // packet. 272 if (transmitList.empty()) { 273 serial_link.schedule(sendEvent, when); 274 } 275 276 transmitList.emplace_back(DeferredPacket(pkt, when)); 277} 278 279void 280SerialLink::SerialLinkMasterPort::trySendTiming() 281{ 282 assert(!transmitList.empty()); 283 284 DeferredPacket req = transmitList.front(); 285 286 assert(req.tick <= curTick()); 287 288 PacketPtr pkt = req.pkt; 289 290 DPRINTF(SerialLink, "trySend request addr 0x%x, queue size %d\n", 291 pkt->getAddr(), transmitList.size()); 292 293 if (sendTimingReq(pkt)) { 294 // send successful 295 transmitList.pop_front(); 296 297 DPRINTF(SerialLink, "trySend request successful\n"); 298 299 // If there are more packets to send, schedule event to try again. 300 if (!transmitList.empty()) { 301 DeferredPacket next_req = transmitList.front(); 302 DPRINTF(SerialLink, "Scheduling next send\n"); 303 304 // Make sure bandwidth limitation is met 305 Cycles cycles = Cycles(divCeil(pkt->getSize() * 8, 306 serial_link.num_lanes * serial_link.link_speed)); 307 Tick t = serial_link.clockEdge(cycles); 308 serial_link.schedule(sendEvent, std::max(next_req.tick, t)); 309 } 310 311 // if we have stalled a request due to a full request queue, 312 // then send a retry at this point, also note that if the 313 // request we stalled was waiting for the response queue 314 // rather than the request queue we might stall it again 315 slavePort.retryStalledReq(); 316 } 317 318 // if the send failed, then we try again once we receive a retry, 319 // and therefore there is no need to take any action 320} 321 322void 323SerialLink::SerialLinkSlavePort::trySendTiming() 324{ 325 assert(!transmitList.empty()); 326 327 DeferredPacket resp = transmitList.front(); 328 329 assert(resp.tick <= curTick()); 330 331 PacketPtr pkt = resp.pkt; 332 333 DPRINTF(SerialLink, "trySend response addr 0x%x, outstanding %d\n", 334 pkt->getAddr(), outstandingResponses); 335 336 if (sendTimingResp(pkt)) { 337 // send successful 338 transmitList.pop_front(); 339 DPRINTF(SerialLink, "trySend response successful\n"); 340 341 assert(outstandingResponses != 0); 342 --outstandingResponses; 343 344 // If there are more packets to send, schedule event to try again. 345 if (!transmitList.empty()) { 346 DeferredPacket next_resp = transmitList.front(); 347 DPRINTF(SerialLink, "Scheduling next send\n"); 348 349 // Make sure bandwidth limitation is met 350 Cycles cycles = Cycles(divCeil(pkt->getSize() * 8, 351 serial_link.num_lanes * serial_link.link_speed)); 352 Tick t = serial_link.clockEdge(cycles); 353 serial_link.schedule(sendEvent, std::max(next_resp.tick, t)); 354 } 355 356 // if there is space in the request queue and we were stalling 357 // a request, it will definitely be possible to accept it now 358 // since there is guaranteed space in the response queue 359 if (!masterPort.reqQueueFull() && retryReq) { 360 DPRINTF(SerialLink, "Request waiting for retry, now retrying\n"); 361 retryReq = false; 362 sendRetryReq(); 363 } 364 } 365 366 // if the send failed, then we try again once we receive a retry, 367 // and therefore there is no need to take any action 368} 369 370void 371SerialLink::SerialLinkMasterPort::recvReqRetry() 372{ 373 trySendTiming(); 374} 375 376void 377SerialLink::SerialLinkSlavePort::recvRespRetry() 378{ 379 trySendTiming(); 380} 381 382Tick 383SerialLink::SerialLinkSlavePort::recvAtomic(PacketPtr pkt) 384{ 385 return delay * serial_link.clockPeriod() + masterPort.sendAtomic(pkt); 386} 387 388void 389SerialLink::SerialLinkSlavePort::recvFunctional(PacketPtr pkt) 390{ 391 pkt->pushLabel(name()); 392 393 // check the response queue 394 for (auto i = transmitList.begin(); i != transmitList.end(); ++i) { 395 if (pkt->checkFunctional((*i).pkt)) { 396 pkt->makeResponse(); 397 return; 398 } 399 } 400 401 // also check the master port's request queue 402 if (masterPort.checkFunctional(pkt)) { 403 return; 404 } 405 406 pkt->popLabel(); 407 408 // fall through if pkt still not satisfied 409 masterPort.sendFunctional(pkt); 410} 411 412bool 413SerialLink::SerialLinkMasterPort::checkFunctional(PacketPtr pkt) 414{ 415 bool found = false; 416 auto i = transmitList.begin(); 417 418 while (i != transmitList.end() && !found) { 419 if (pkt->checkFunctional((*i).pkt)) { 420 pkt->makeResponse(); 421 found = true; 422 } 423 ++i; 424 } 425 426 return found; 427} 428 429AddrRangeList 430SerialLink::SerialLinkSlavePort::getAddrRanges() const 431{ 432 return ranges; 433} 434 435SerialLink * 436SerialLinkParams::create() 437{ 438 return new SerialLink(this); 439} |