coherent_xbar.hh revision 11859
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) 2002-2005 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: Ron Dreslinski 41 * Ali Saidi 42 * Andreas Hansson 43 * William Wang 44 */ 45 46/** 47 * @file 48 * Declaration of a coherent crossbar. 49 */ 50 51#ifndef __MEM_COHERENT_XBAR_HH__ 52#define __MEM_COHERENT_XBAR_HH__ 53 54#include <unordered_set> 55 56#include "mem/snoop_filter.hh" 57#include "mem/xbar.hh" 58#include "params/CoherentXBar.hh" 59 60/** 61 * A coherent crossbar connects a number of (potentially) snooping 62 * masters and slaves, and routes the request and response packets 63 * based on the address, and also forwards all requests to the 64 * snoopers and deals with the snoop responses. 65 * 66 * The coherent crossbar can be used as a template for modelling QPI, 67 * HyperTransport, ACE and coherent OCP buses, and is typically used 68 * for the L1-to-L2 buses and as the main system interconnect. @sa 69 * \ref gem5MemorySystem "gem5 Memory System" 70 */ 71class CoherentXBar : public BaseXBar 72{ 73 74 protected: 75 76 /** 77 * Declare the layers of this crossbar, one vector for requests, 78 * one for responses, and one for snoop responses 79 */ 80 std::vector<ReqLayer*> reqLayers; 81 std::vector<RespLayer*> respLayers; 82 std::vector<SnoopRespLayer*> snoopLayers; 83 84 /** 85 * Declaration of the coherent crossbar slave port type, one will 86 * be instantiated for each of the master ports connecting to the 87 * crossbar. 88 */ 89 class CoherentXBarSlavePort : public QueuedSlavePort 90 { 91 92 private: 93 94 /** A reference to the crossbar to which this port belongs. */ 95 CoherentXBar &xbar; 96 97 /** A normal packet queue used to store responses. */ 98 RespPacketQueue queue; 99 100 public: 101 102 CoherentXBarSlavePort(const std::string &_name, 103 CoherentXBar &_xbar, PortID _id) 104 : QueuedSlavePort(_name, &_xbar, queue, _id), xbar(_xbar), 105 queue(_xbar, *this) 106 { } 107 108 protected: 109 110 /** 111 * When receiving a timing request, pass it to the crossbar. 112 */ 113 virtual bool recvTimingReq(PacketPtr pkt) 114 { return xbar.recvTimingReq(pkt, id); } 115 116 /** 117 * When receiving a timing snoop response, pass it to the crossbar. 118 */ 119 virtual bool recvTimingSnoopResp(PacketPtr pkt) 120 { return xbar.recvTimingSnoopResp(pkt, id); } 121 122 /** 123 * When receiving an atomic request, pass it to the crossbar. 124 */ 125 virtual Tick recvAtomic(PacketPtr pkt) 126 { return xbar.recvAtomic(pkt, id); } 127 128 /** 129 * When receiving a functional request, pass it to the crossbar. 130 */ 131 virtual void recvFunctional(PacketPtr pkt) 132 { xbar.recvFunctional(pkt, id); } 133 134 /** 135 * Return the union of all adress ranges seen by this crossbar. 136 */ 137 virtual AddrRangeList getAddrRanges() const 138 { return xbar.getAddrRanges(); } 139 140 }; 141 142 /** 143 * Declaration of the coherent crossbar master port type, one will be 144 * instantiated for each of the slave interfaces connecting to the 145 * crossbar. 146 */ 147 class CoherentXBarMasterPort : public MasterPort 148 { 149 private: 150 /** A reference to the crossbar to which this port belongs. */ 151 CoherentXBar &xbar; 152 153 public: 154 155 CoherentXBarMasterPort(const std::string &_name, 156 CoherentXBar &_xbar, PortID _id) 157 : MasterPort(_name, &_xbar, _id), xbar(_xbar) 158 { } 159 160 protected: 161 162 /** 163 * Determine if this port should be considered a snooper. For 164 * a coherent crossbar master port this is always true. 165 * 166 * @return a boolean that is true if this port is snooping 167 */ 168 virtual bool isSnooping() const 169 { return true; } 170 171 /** 172 * When receiving a timing response, pass it to the crossbar. 173 */ 174 virtual bool recvTimingResp(PacketPtr pkt) 175 { return xbar.recvTimingResp(pkt, id); } 176 177 /** 178 * When receiving a timing snoop request, pass it to the crossbar. 179 */ 180 virtual void recvTimingSnoopReq(PacketPtr pkt) 181 { return xbar.recvTimingSnoopReq(pkt, id); } 182 183 /** 184 * When receiving an atomic snoop request, pass it to the crossbar. 185 */ 186 virtual Tick recvAtomicSnoop(PacketPtr pkt) 187 { return xbar.recvAtomicSnoop(pkt, id); } 188 189 /** 190 * When receiving a functional snoop request, pass it to the crossbar. 191 */ 192 virtual void recvFunctionalSnoop(PacketPtr pkt) 193 { xbar.recvFunctionalSnoop(pkt, id); } 194 195 /** When reciving a range change from the peer port (at id), 196 pass it to the crossbar. */ 197 virtual void recvRangeChange() 198 { xbar.recvRangeChange(id); } 199 200 /** When reciving a retry from the peer port (at id), 201 pass it to the crossbar. */ 202 virtual void recvReqRetry() 203 { xbar.recvReqRetry(id); } 204 205 }; 206 207 /** 208 * Internal class to bridge between an incoming snoop response 209 * from a slave port and forwarding it through an outgoing slave 210 * port. It is effectively a dangling master port. 211 */ 212 class SnoopRespPort : public MasterPort 213 { 214 215 private: 216 217 /** The port which we mirror internally. */ 218 QueuedSlavePort& slavePort; 219 220 public: 221 222 /** 223 * Create a snoop response port that mirrors a given slave port. 224 */ 225 SnoopRespPort(QueuedSlavePort& slave_port, CoherentXBar& _xbar) : 226 MasterPort(slave_port.name() + ".snoopRespPort", &_xbar), 227 slavePort(slave_port) { } 228 229 /** 230 * Override the sending of retries and pass them on through 231 * the mirrored slave port. 232 */ 233 void sendRetryResp() { 234 // forward it as a snoop response retry 235 slavePort.sendRetrySnoopResp(); 236 } 237 238 /** 239 * Provided as necessary. 240 */ 241 void recvReqRetry() { panic("SnoopRespPort should never see retry\n"); } 242 243 /** 244 * Provided as necessary. 245 */ 246 bool recvTimingResp(PacketPtr pkt) 247 { 248 panic("SnoopRespPort should never see timing response\n"); 249 return false; 250 } 251 252 }; 253 254 std::vector<SnoopRespPort*> snoopRespPorts; 255 256 std::vector<QueuedSlavePort*> snoopPorts; 257 258 /** 259 * Store the outstanding requests that we are expecting snoop 260 * responses from so we can determine which snoop responses we 261 * generated and which ones were merely forwarded. 262 */ 263 std::unordered_set<RequestPtr> outstandingSnoop; 264 265 /** 266 * Keep a pointer to the system to be allow to querying memory system 267 * properties. 268 */ 269 System *system; 270 271 /** A snoop filter that tracks cache line residency and can restrict the 272 * broadcast needed for probes. NULL denotes an absent filter. */ 273 SnoopFilter *snoopFilter; 274 275 /** Cycles of snoop response latency.*/ 276 const Cycles snoopResponseLatency; 277 278 /** Is this crossbar the point of coherency? **/ 279 const bool pointOfCoherency; 280 281 /** 282 * Upstream caches need this packet until true is returned, so 283 * hold it for deletion until a subsequent call 284 */ 285 std::unique_ptr<Packet> pendingDelete; 286 287 /** Function called by the port when the crossbar is recieving a Timing 288 request packet.*/ 289 bool recvTimingReq(PacketPtr pkt, PortID slave_port_id); 290 291 /** Function called by the port when the crossbar is recieving a Timing 292 response packet.*/ 293 bool recvTimingResp(PacketPtr pkt, PortID master_port_id); 294 295 /** Function called by the port when the crossbar is recieving a timing 296 snoop request.*/ 297 void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id); 298 299 /** Function called by the port when the crossbar is recieving a timing 300 snoop response.*/ 301 bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id); 302 303 /** Timing function called by port when it is once again able to process 304 * requests. */ 305 void recvReqRetry(PortID master_port_id); 306 307 /** 308 * Forward a timing packet to our snoopers, potentially excluding 309 * one of the connected coherent masters to avoid sending a packet 310 * back to where it came from. 311 * 312 * @param pkt Packet to forward 313 * @param exclude_slave_port_id Id of slave port to exclude 314 */ 315 void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id) { 316 forwardTiming(pkt, exclude_slave_port_id, snoopPorts); 317 } 318 319 /** 320 * Forward a timing packet to a selected list of snoopers, potentially 321 * excluding one of the connected coherent masters to avoid sending a packet 322 * back to where it came from. 323 * 324 * @param pkt Packet to forward 325 * @param exclude_slave_port_id Id of slave port to exclude 326 * @param dests Vector of destination ports for the forwarded pkt 327 */ 328 void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id, 329 const std::vector<QueuedSlavePort*>& dests); 330 331 /** Function called by the port when the crossbar is recieving a Atomic 332 transaction.*/ 333 Tick recvAtomic(PacketPtr pkt, PortID slave_port_id); 334 335 /** Function called by the port when the crossbar is recieving an 336 atomic snoop transaction.*/ 337 Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id); 338 339 /** 340 * Forward an atomic packet to our snoopers, potentially excluding 341 * one of the connected coherent masters to avoid sending a packet 342 * back to where it came from. 343 * 344 * @param pkt Packet to forward 345 * @param exclude_slave_port_id Id of slave port to exclude 346 * 347 * @return a pair containing the snoop response and snoop latency 348 */ 349 std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt, 350 PortID exclude_slave_port_id) 351 { 352 return forwardAtomic(pkt, exclude_slave_port_id, InvalidPortID, 353 snoopPorts); 354 } 355 356 /** 357 * Forward an atomic packet to a selected list of snoopers, potentially 358 * excluding one of the connected coherent masters to avoid sending a packet 359 * back to where it came from. 360 * 361 * @param pkt Packet to forward 362 * @param exclude_slave_port_id Id of slave port to exclude 363 * @param source_master_port_id Id of the master port for snoops from below 364 * @param dests Vector of destination ports for the forwarded pkt 365 * 366 * @return a pair containing the snoop response and snoop latency 367 */ 368 std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt, 369 PortID exclude_slave_port_id, 370 PortID source_master_port_id, 371 const std::vector<QueuedSlavePort*>& 372 dests); 373 374 /** Function called by the port when the crossbar is recieving a Functional 375 transaction.*/ 376 void recvFunctional(PacketPtr pkt, PortID slave_port_id); 377 378 /** Function called by the port when the crossbar is recieving a functional 379 snoop transaction.*/ 380 void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id); 381 382 /** 383 * Forward a functional packet to our snoopers, potentially 384 * excluding one of the connected coherent masters to avoid 385 * sending a packet back to where it came from. 386 * 387 * @param pkt Packet to forward 388 * @param exclude_slave_port_id Id of slave port to exclude 389 */ 390 void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id); 391 392 /** 393 * Determine if the crossbar should sink the packet, as opposed to 394 * forwarding it, or responding. 395 */ 396 bool sinkPacket(const PacketPtr pkt) const; 397 398 Stats::Scalar snoops; 399 Stats::Scalar snoopTraffic; 400 Stats::Distribution snoopFanout; 401 402 public: 403 404 virtual void init(); 405 406 CoherentXBar(const CoherentXBarParams *p); 407 408 virtual ~CoherentXBar(); 409 410 virtual void regStats(); 411}; 412 413#endif //__MEM_COHERENT_XBAR_HH__ 414