serial_link.cc revision 12084:5a3769ff3d55
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), 70 sendEvent([this]{ trySendTiming(); }, _name) 71{ 72} 73 74SerialLink::SerialLinkMasterPort::SerialLinkMasterPort(const std::string& 75 _name, SerialLink& _serial_link, 76 SerialLinkSlavePort& _slavePort, 77 Cycles _delay, int _req_limit) 78 : MasterPort(_name, &_serial_link), serial_link(_serial_link), 79 slavePort(_slavePort), delay(_delay), reqQueueLimit(_req_limit), 80 sendEvent([this]{ trySendTiming(); }, _name) 81{ 82} 83 84SerialLink::SerialLink(SerialLinkParams *p) 85 : MemObject(p), 86 slavePort(p->name + ".slave", *this, masterPort, 87 ticksToCycles(p->delay), p->resp_size, p->ranges), 88 masterPort(p->name + ".master", *this, slavePort, 89 ticksToCycles(p->delay), p->req_size), 90 num_lanes(p->num_lanes), 91 link_speed(p->link_speed) 92 93{ 94} 95 96BaseMasterPort& 97SerialLink::getMasterPort(const std::string &if_name, PortID idx) 98{ 99 if (if_name == "master") 100 return masterPort; 101 else 102 // pass it along to our super class 103 return MemObject::getMasterPort(if_name, idx); 104} 105 106BaseSlavePort& 107SerialLink::getSlavePort(const std::string &if_name, PortID idx) 108{ 109 if (if_name == "slave") 110 return slavePort; 111 else 112 // pass it along to our super class 113 return MemObject::getSlavePort(if_name, idx); 114} 115 116void 117SerialLink::init() 118{ 119 // make sure both sides are connected and have the same block size 120 if (!slavePort.isConnected() || !masterPort.isConnected()) 121 fatal("Both ports of a serial_link must be connected.\n"); 122 123 // notify the master side of our address ranges 124 slavePort.sendRangeChange(); 125} 126 127bool 128SerialLink::SerialLinkSlavePort::respQueueFull() const 129{ 130 return outstandingResponses == respQueueLimit; 131} 132 133bool 134SerialLink::SerialLinkMasterPort::reqQueueFull() const 135{ 136 return transmitList.size() == reqQueueLimit; 137} 138 139bool 140SerialLink::SerialLinkMasterPort::recvTimingResp(PacketPtr pkt) 141{ 142 // all checks are done when the request is accepted on the slave 143 // side, so we are guaranteed to have space for the response 144 DPRINTF(SerialLink, "recvTimingResp: %s addr 0x%x\n", 145 pkt->cmdString(), pkt->getAddr()); 146 147 DPRINTF(SerialLink, "Request queue size: %d\n", transmitList.size()); 148 149 // @todo: We need to pay for this and not just zero it out 150 pkt->headerDelay = pkt->payloadDelay = 0; 151 152 // This is similar to what happens for the request packets: 153 // The serializer will start serialization as soon as it receives the 154 // first flit, but the deserializer (at the host side in this case), will 155 // have to wait to receive the whole packet. So we only account for the 156 // deserialization latency. 157 Cycles cycles = delay; 158 cycles += Cycles(divCeil(pkt->getSize() * 8, serial_link.num_lanes 159 * serial_link.link_speed)); 160 Tick t = serial_link.clockEdge(cycles); 161 162 //@todo: If the processor sends two uncached requests towards HMC and the 163 // second one is smaller than the first one. It may happen that the second 164 // one crosses this link faster than the first one (because the packet 165 // waits in the link based on its size). This can reorder the received 166 // response. 167 slavePort.schedTimingResp(pkt, t); 168 169 return true; 170} 171 172bool 173SerialLink::SerialLinkSlavePort::recvTimingReq(PacketPtr pkt) 174{ 175 DPRINTF(SerialLink, "recvTimingReq: %s addr 0x%x\n", 176 pkt->cmdString(), pkt->getAddr()); 177 178 // we should not see a timing request if we are already in a retry 179 assert(!retryReq); 180 181 DPRINTF(SerialLink, "Response queue size: %d outresp: %d\n", 182 transmitList.size(), outstandingResponses); 183 184 // if the request queue is full then there is no hope 185 if (masterPort.reqQueueFull()) { 186 DPRINTF(SerialLink, "Request queue full\n"); 187 retryReq = true; 188 } else if ( !retryReq ) { 189 // look at the response queue if we expect to see a response 190 bool expects_response = pkt->needsResponse() && 191 !pkt->cacheResponding(); 192 if (expects_response) { 193 if (respQueueFull()) { 194 DPRINTF(SerialLink, "Response queue full\n"); 195 retryReq = true; 196 } else { 197 // ok to send the request with space for the response 198 DPRINTF(SerialLink, "Reserving space for response\n"); 199 assert(outstandingResponses != respQueueLimit); 200 ++outstandingResponses; 201 202 // no need to set retryReq to false as this is already the 203 // case 204 } 205 } 206 207 if (!retryReq) { 208 // @todo: We need to pay for this and not just zero it out 209 pkt->headerDelay = pkt->payloadDelay = 0; 210 211 // We assume that the serializer component at the transmitter side 212 // does not need to receive the whole packet to start the 213 // serialization (this assumption is consistent with the HMC 214 // standard). But the deserializer waits for the complete packet 215 // to check its integrity first. So everytime a packet crosses a 216 // serial link, we should account for its deserialization latency 217 // only. 218 Cycles cycles = delay; 219 cycles += Cycles(divCeil(pkt->getSize() * 8, 220 serial_link.num_lanes * serial_link.link_speed)); 221 Tick t = serial_link.clockEdge(cycles); 222 223 //@todo: If the processor sends two uncached requests towards HMC 224 // and the second one is smaller than the first one. It may happen 225 // that the second one crosses this link faster than the first one 226 // (because the packet waits in the link based on its size). 227 // This can reorder the received response. 228 masterPort.schedTimingReq(pkt, t); 229 } 230 } 231 232 // remember that we are now stalling a packet and that we have to 233 // tell the sending master to retry once space becomes available, 234 // we make no distinction whether the stalling is due to the 235 // request queue or response queue being full 236 return !retryReq; 237} 238 239void 240SerialLink::SerialLinkSlavePort::retryStalledReq() 241{ 242 if (retryReq) { 243 DPRINTF(SerialLink, "Request waiting for retry, now retrying\n"); 244 retryReq = false; 245 sendRetryReq(); 246 } 247} 248 249void 250SerialLink::SerialLinkMasterPort::schedTimingReq(PacketPtr pkt, Tick when) 251{ 252 // If we're about to put this packet at the head of the queue, we 253 // need to schedule an event to do the transmit. Otherwise there 254 // should already be an event scheduled for sending the head 255 // packet. 256 if (transmitList.empty()) { 257 serial_link.schedule(sendEvent, when); 258 } 259 260 assert(transmitList.size() != reqQueueLimit); 261 262 transmitList.emplace_back(DeferredPacket(pkt, when)); 263} 264 265 266void 267SerialLink::SerialLinkSlavePort::schedTimingResp(PacketPtr pkt, Tick when) 268{ 269 // If we're about to put this packet at the head of the queue, we 270 // need to schedule an event to do the transmit. Otherwise there 271 // should already be an event scheduled for sending the head 272 // packet. 273 if (transmitList.empty()) { 274 serial_link.schedule(sendEvent, when); 275 } 276 277 transmitList.emplace_back(DeferredPacket(pkt, when)); 278} 279 280void 281SerialLink::SerialLinkMasterPort::trySendTiming() 282{ 283 assert(!transmitList.empty()); 284 285 DeferredPacket req = transmitList.front(); 286 287 assert(req.tick <= curTick()); 288 289 PacketPtr pkt = req.pkt; 290 291 DPRINTF(SerialLink, "trySend request addr 0x%x, queue size %d\n", 292 pkt->getAddr(), transmitList.size()); 293 294 if (sendTimingReq(pkt)) { 295 // send successful 296 transmitList.pop_front(); 297 298 DPRINTF(SerialLink, "trySend request successful\n"); 299 300 // If there are more packets to send, schedule event to try again. 301 if (!transmitList.empty()) { 302 DeferredPacket next_req = transmitList.front(); 303 DPRINTF(SerialLink, "Scheduling next send\n"); 304 305 // Make sure bandwidth limitation is met 306 Cycles cycles = Cycles(divCeil(pkt->getSize() * 8, 307 serial_link.num_lanes * serial_link.link_speed)); 308 Tick t = serial_link.clockEdge(cycles); 309 serial_link.schedule(sendEvent, std::max(next_req.tick, t)); 310 } 311 312 // if we have stalled a request due to a full request queue, 313 // then send a retry at this point, also note that if the 314 // request we stalled was waiting for the response queue 315 // rather than the request queue we might stall it again 316 slavePort.retryStalledReq(); 317 } 318 319 // if the send failed, then we try again once we receive a retry, 320 // and therefore there is no need to take any action 321} 322 323void 324SerialLink::SerialLinkSlavePort::trySendTiming() 325{ 326 assert(!transmitList.empty()); 327 328 DeferredPacket resp = transmitList.front(); 329 330 assert(resp.tick <= curTick()); 331 332 PacketPtr pkt = resp.pkt; 333 334 DPRINTF(SerialLink, "trySend response addr 0x%x, outstanding %d\n", 335 pkt->getAddr(), outstandingResponses); 336 337 if (sendTimingResp(pkt)) { 338 // send successful 339 transmitList.pop_front(); 340 DPRINTF(SerialLink, "trySend response successful\n"); 341 342 assert(outstandingResponses != 0); 343 --outstandingResponses; 344 345 // If there are more packets to send, schedule event to try again. 346 if (!transmitList.empty()) { 347 DeferredPacket next_resp = transmitList.front(); 348 DPRINTF(SerialLink, "Scheduling next send\n"); 349 350 // Make sure bandwidth limitation is met 351 Cycles cycles = Cycles(divCeil(pkt->getSize() * 8, 352 serial_link.num_lanes * serial_link.link_speed)); 353 Tick t = serial_link.clockEdge(cycles); 354 serial_link.schedule(sendEvent, std::max(next_resp.tick, t)); 355 } 356 357 // if there is space in the request queue and we were stalling 358 // a request, it will definitely be possible to accept it now 359 // since there is guaranteed space in the response queue 360 if (!masterPort.reqQueueFull() && retryReq) { 361 DPRINTF(SerialLink, "Request waiting for retry, now retrying\n"); 362 retryReq = false; 363 sendRetryReq(); 364 } 365 } 366 367 // if the send failed, then we try again once we receive a retry, 368 // and therefore there is no need to take any action 369} 370 371void 372SerialLink::SerialLinkMasterPort::recvReqRetry() 373{ 374 trySendTiming(); 375} 376 377void 378SerialLink::SerialLinkSlavePort::recvRespRetry() 379{ 380 trySendTiming(); 381} 382 383Tick 384SerialLink::SerialLinkSlavePort::recvAtomic(PacketPtr pkt) 385{ 386 return delay * serial_link.clockPeriod() + masterPort.sendAtomic(pkt); 387} 388 389void 390SerialLink::SerialLinkSlavePort::recvFunctional(PacketPtr pkt) 391{ 392 pkt->pushLabel(name()); 393 394 // check the response queue 395 for (auto i = transmitList.begin(); i != transmitList.end(); ++i) { 396 if (pkt->checkFunctional((*i).pkt)) { 397 pkt->makeResponse(); 398 return; 399 } 400 } 401 402 // also check the master port's request queue 403 if (masterPort.checkFunctional(pkt)) { 404 return; 405 } 406 407 pkt->popLabel(); 408 409 // fall through if pkt still not satisfied 410 masterPort.sendFunctional(pkt); 411} 412 413bool 414SerialLink::SerialLinkMasterPort::checkFunctional(PacketPtr pkt) 415{ 416 bool found = false; 417 auto i = transmitList.begin(); 418 419 while (i != transmitList.end() && !found) { 420 if (pkt->checkFunctional((*i).pkt)) { 421 pkt->makeResponse(); 422 found = true; 423 } 424 ++i; 425 } 426 427 return found; 428} 429 430AddrRangeList 431SerialLink::SerialLinkSlavePort::getAddrRanges() const 432{ 433 return ranges; 434} 435 436SerialLink * 437SerialLinkParams::create() 438{ 439 return new SerialLink(this); 440} 441