src/dev/net/etherswitch.cc

   1 /*
   2  * Copyright (c) 2014 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /* @file
  30  * Device model for an ethernet switch
  31  */
  32
  33 #include "dev/net/etherswitch.hh"
  34
  35 #include "base/random.hh"
  36 #include "base/trace.hh"
  37 #include "debug/EthernetAll.hh"
  38 #include "sim/core.hh"
  39
  40 using namespace std;
  41
  42 EtherSwitch::EtherSwitch(const Params *p)
  43     : SimObject(p), ttl(p->time_to_live)
  44 {
  45     for (int i = 0; i < p->port_interface_connection_count; ++i) {
  46         std::string interfaceName = csprintf("%s.interface%d", name(), i);
  47         Interface *interface = new Interface(interfaceName, this,
  48                                         p->output_buffer_size, p->delay,
  49                                         p->delay_var, p->fabric_speed, i);
  50         interfaces.push_back(interface);
  51     }
  52 }
  53
  54 EtherSwitch::~EtherSwitch()
  55 {
  56     for (auto it : interfaces)
  57         delete it;
  58
  59     interfaces.clear();
  60 }
  61
  62 Port &
  63 EtherSwitch::getPort(const std::string &if_name, PortID idx)
  64 {
  65     if (if_name == "interface") {
  66         panic_if(idx < 0 || idx >= interfaces.size(), "index out of bounds");
  67         return *interfaces.at(idx);
  68     }
  69
  70     return SimObject::getPort(if_name, idx);
  71 }
  72
  73 bool
  74 EtherSwitch::Interface::PortFifo::push(EthPacketPtr ptr, unsigned senderId)
  75 {
  76     assert(ptr->length);
  77
  78     _size += ptr->length;
  79     fifo.emplace_hint(fifo.end(), ptr, curTick(), senderId);
  80
  81     // Drop the extra pushed packets from end of the fifo
  82     while (avail() < 0) {
  83         DPRINTF(Ethernet, "Fifo is full. Drop packet: len=%d\n",
  84                 std::prev(fifo.end())->packet->length);
  85
  86         _size -= std::prev(fifo.end())->packet->length;
  87         fifo.erase(std::prev(fifo.end()));
  88     }
  89
  90     if (empty()) {
  91         warn("EtherSwitch: Packet length (%d) exceeds the maximum storage "
  92              "capacity of port fifo (%d)", ptr->length, _maxsize);
  93     }
  94
  95     // Return true if the newly pushed packet gets inserted
  96     // at the head of the queue, otherwise return false
  97     // We need this information to deschedule the event that has been
  98     // scheduled for the old head of queue packet and schedule a new one
  99     if (!empty() && fifo.begin()->packet == ptr) {
 100         return true;
 101     }
 102     return false;
 103 }
 104
 105 void
 106 EtherSwitch::Interface::PortFifo::pop()
 107 {
 108     if (empty())
 109         return;
 110
 111     assert(_size >= fifo.begin()->packet->length);
 112     // Erase the packet at the head of the queue
 113     _size -= fifo.begin()->packet->length;
 114     fifo.erase(fifo.begin());
 115 }
 116
 117 void
 118 EtherSwitch::Interface::PortFifo::clear()
 119 {
 120     fifo.clear();
 121     _size = 0;
 122 }
 123
 124 EtherSwitch::Interface::Interface(const std::string &name,
 125                                   EtherSwitch *etherSwitch,
 126                                   uint64_t outputBufferSize, Tick delay,
 127                                   Tick delay_var, double rate, unsigned id)
 128     : EtherInt(name), ticksPerByte(rate), switchDelay(delay),
 129       delayVar(delay_var), interfaceId(id), parent(etherSwitch),
 130       outputFifo(name + ".outputFifo", outputBufferSize),
 131       txEvent([this]{ transmit(); }, name)
 132 {
 133 }
 134
 135 bool
 136 EtherSwitch::Interface::recvPacket(EthPacketPtr packet)
 137 {
 138     Net::EthAddr destMacAddr(packet->data);
 139     Net::EthAddr srcMacAddr(&packet->data[6]);
 140
 141     learnSenderAddr(srcMacAddr, this);
 142     Interface *receiver = lookupDestPort(destMacAddr);
 143
 144     if (!receiver || destMacAddr.multicast() || destMacAddr.broadcast()) {
 145         for (auto it : parent->interfaces)
 146             if (it != this)
 147                 it->enqueue(packet, interfaceId);
 148     } else {
 149         DPRINTF(Ethernet, "sending packet from MAC %x on port "
 150                 "%s to MAC %x on port %s\n", uint64_t(srcMacAddr),
 151                 this->name(), uint64_t(destMacAddr), receiver->name());
 152
 153         receiver->enqueue(packet, interfaceId);
 154     }
 155     // At the output port, we either have buffer space (no drop) or
 156     // don't (drop packet); in both cases packet is received on
 157     // the interface successfully and there is no notion of busy
 158     // interface here (as we don't have inputFifo)
 159     return true;
 160 }
 161
 162 void
 163 EtherSwitch::Interface::enqueue(EthPacketPtr packet, unsigned senderId)
 164 {
 165     // assuming per-interface transmission events,
 166     // if the newly push packet gets inserted at the head of the queue
 167     // (either there was nothing in the queue or the priority of the new
 168     // packet was higher than the packets already in the fifo)
 169     // then we need to schedule an event at
 170     // "curTick" + "switchingDelay of the packet at the head of the fifo"
 171     // to send this packet out the external link
 172     // otherwise, there is already a txEvent scheduled
 173     if (outputFifo.push(packet, senderId)) {
 174         parent->reschedule(txEvent, curTick() + switchingDelay(), true);
 175     }
 176 }
 177
 178 void
 179 EtherSwitch::Interface::transmit()
 180 {
 181     // there should be something in the output queue
 182     assert(!outputFifo.empty());
 183
 184     if (!sendPacket(outputFifo.front())) {
 185         DPRINTF(Ethernet, "output port busy...retry later\n");
 186         if (!txEvent.scheduled())
 187             parent->schedule(txEvent, curTick() + retryTime);
 188     } else {
 189         DPRINTF(Ethernet, "packet sent: len=%d\n", outputFifo.front()->length);
 190         outputFifo.pop();
 191         // schedule an event to send the pkt at
 192         // the head of queue, if there is any
 193         if (!outputFifo.empty()) {
 194             parent->schedule(txEvent, curTick() + switchingDelay());
 195         }
 196     }
 197 }
 198
 199 Tick
 200 EtherSwitch::Interface::switchingDelay()
 201 {
 202     Tick delay = (Tick)ceil(((double)outputFifo.front()->simLength
 203                                      * ticksPerByte) + 1.0);
 204     if (delayVar != 0)
 205                 delay += random_mt.random<Tick>(0, delayVar);
 206     delay += switchDelay;
 207     return delay;
 208 }
 209
 210 EtherSwitch::Interface*
 211 EtherSwitch::Interface::lookupDestPort(Net::EthAddr destMacAddr)
 212 {
 213     auto it = parent->forwardingTable.find(uint64_t(destMacAddr));
 214
 215     if (it == parent->forwardingTable.end()) {
 216         DPRINTF(Ethernet, "no entry in forwaring table for MAC: "
 217                 "%x\n", uint64_t(destMacAddr));
 218         return nullptr;
 219     }
 220
 221     // check if this entry is valid based on TTL and lastUseTime
 222     if ((curTick() - it->second.lastUseTime) > parent->ttl) {
 223         // TTL for this mapping has been expired, so this item is not
 224         // valide anymore, let's remove it from the map
 225         parent->forwardingTable.erase(it);
 226         return nullptr;
 227     }
 228
 229     DPRINTF(Ethernet, "found entry for MAC address %x on port %s\n",
 230             uint64_t(destMacAddr), it->second.interface->name());
 231     return it->second.interface;
 232 }
 233
 234 void
 235 EtherSwitch::Interface::learnSenderAddr(Net::EthAddr srcMacAddr,
 236                                           Interface *sender)
 237 {
 238     // learn the port for the sending MAC address
 239     auto it = parent->forwardingTable.find(uint64_t(srcMacAddr));
 240
 241     // if the port for sender's MAC address is not cached,
 242     // cache it now, otherwise just update lastUseTime time
 243     if (it == parent->forwardingTable.end()) {
 244         DPRINTF(Ethernet, "adding forwarding table entry for MAC "
 245                 " address %x on port %s\n", uint64_t(srcMacAddr),
 246                 sender->name());
 247         EtherSwitch::SwitchTableEntry forwardingTableEntry;
 248         forwardingTableEntry.interface = sender;
 249         forwardingTableEntry.lastUseTime = curTick();
 250         parent->forwardingTable.insert(std::make_pair(uint64_t(srcMacAddr),
 251             forwardingTableEntry));
 252     } else {
 253         it->second.lastUseTime = curTick();
 254     }
 255 }
 256
 257 void
 258 EtherSwitch::serialize(CheckpointOut &cp) const
 259 {
 260     for (auto it : interfaces)
 261         it->serializeSection(cp, it->name());
 262
 263 }
 264
 265 void
 266 EtherSwitch::unserialize(CheckpointIn &cp)
 267 {
 268     for (auto it : interfaces)
 269         it->unserializeSection(cp, it->name());
 270
 271 }
 272
 273 void
 274 EtherSwitch::Interface::serialize(CheckpointOut &cp) const
 275 {
 276     bool event_scheduled = txEvent.scheduled();
 277     SERIALIZE_SCALAR(event_scheduled);
 278
 279     if (event_scheduled) {
 280         Tick event_time = txEvent.when();
 281         SERIALIZE_SCALAR(event_time);
 282     }
 283     outputFifo.serializeSection(cp, "outputFifo");
 284 }
 285
 286 void
 287 EtherSwitch::Interface::unserialize(CheckpointIn &cp)
 288 {
 289     bool event_scheduled;
 290     UNSERIALIZE_SCALAR(event_scheduled);
 291
 292     if (event_scheduled) {
 293         Tick event_time;
 294         UNSERIALIZE_SCALAR(event_time);
 295         parent->schedule(txEvent, event_time);
 296     }
 297     outputFifo.unserializeSection(cp, "outputFifo");
 298 }
 299
 300 void
 301 EtherSwitch::Interface::PortFifoEntry::serialize(CheckpointOut &cp) const
 302 {
 303     packet->serialize("packet", cp);
 304     SERIALIZE_SCALAR(recvTick);
 305     SERIALIZE_SCALAR(srcId);
 306 }
 307
 308 void
 309 EtherSwitch::Interface::PortFifoEntry::unserialize(CheckpointIn &cp)
 310 {
 311     packet = make_shared<EthPacketData>(16384);
 312     packet->unserialize("packet", cp);
 313     UNSERIALIZE_SCALAR(recvTick);
 314     UNSERIALIZE_SCALAR(srcId);
 315 }
 316
 317 void
 318 EtherSwitch::Interface::PortFifo::serialize(CheckpointOut &cp) const
 319 {
 320     SERIALIZE_SCALAR(_size);
 321     int fifosize = fifo.size();
 322
 323     SERIALIZE_SCALAR(fifosize);
 324
 325     int i = 0;
 326     for (const auto &entry : fifo)
 327         entry.serializeSection(cp, csprintf("entry%d", i++));
 328 }
 329
 330 void
 331 EtherSwitch::Interface::PortFifo::unserialize(CheckpointIn &cp)
 332 {
 333     UNSERIALIZE_SCALAR(_size);
 334     int fifosize;
 335
 336     UNSERIALIZE_SCALAR(fifosize);
 337     fifo.clear();
 338
 339     for (int i = 0; i < fifosize; ++i) {
 340         PortFifoEntry entry(nullptr, 0, 0);
 341
 342         entry.unserializeSection(cp, csprintf("entry%d", i));
 343
 344         fifo.insert(entry);
 345
 346     }
 347 }
 348
 349 EtherSwitch *
 350 EtherSwitchParams::create()
 351 {
 352     return new EtherSwitch(this);
 353 }