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  * Authors: Anthony Gutierrez
  29  *          Mohammad Alian
  30  */
  31
  32 /* @file
  33  * Device model for an ethernet switch
  34  */
  35
  36 #include "dev/net/etherswitch.hh"
  37
  38 #include "base/random.hh"
  39 #include "base/trace.hh"
  40 #include "debug/EthernetAll.hh"
  41 #include "sim/core.hh"
  42
  43 using namespace std;
  44
  45 EtherSwitch::EtherSwitch(const Params *p)
  46     : EtherObject(p), ttl(p->time_to_live)
  47 {
  48     for (int i = 0; i < p->port_interface_connection_count; ++i) {
  49         std::string interfaceName = csprintf("%s.interface%d", name(), i);
  50         Interface *interface = new Interface(interfaceName, this,
  51                                         p->output_buffer_size, p->delay,
  52                                         p->delay_var, p->fabric_speed, i);
  53         interfaces.push_back(interface);
  54     }
  55 }
  56
  57 EtherSwitch::~EtherSwitch()
  58 {
  59     for (auto it : interfaces)
  60         delete it;
  61
  62     interfaces.clear();
  63 }
  64
  65 EtherInt*
  66 EtherSwitch::getEthPort(const std::string &if_name, int idx)
  67 {
  68     if (idx < 0 || idx >= interfaces.size())
  69         return nullptr;
  70
  71     Interface *interface = interfaces.at(idx);
  72     panic_if(interface->getPeer(), "interface already connected\n");
  73
  74     return interface;
  75 }
  76
  77 bool
  78 EtherSwitch::Interface::PortFifo::push(EthPacketPtr ptr, unsigned senderId)
  79 {
  80     assert(ptr->length);
  81
  82     _size += ptr->length;
  83     fifo.emplace_hint(fifo.end(), ptr, curTick(), senderId);
  84
  85     // Drop the extra pushed packets from end of the fifo
  86     while (avail() < 0) {
  87         DPRINTF(Ethernet, "Fifo is full. Drop packet: len=%d\n",
  88                 std::prev(fifo.end())->packet->length);
  89
  90         _size -= std::prev(fifo.end())->packet->length;
  91         fifo.erase(std::prev(fifo.end()));
  92     }
  93
  94     if (empty()) {
  95         warn("EtherSwitch: Packet length (%d) exceeds the maximum storage "
  96              "capacity of port fifo (%d)", ptr->length, _maxsize);
  97     }
  98
  99     // Return true if the newly pushed packet gets inserted
 100     // at the head of the queue, otherwise return false
 101     // We need this information to deschedule the event that has been
 102     // scheduled for the old head of queue packet and schedule a new one
 103     if (!empty() && fifo.begin()->packet == ptr) {
 104         return true;
 105     }
 106     return false;
 107 }
 108
 109 void
 110 EtherSwitch::Interface::PortFifo::pop()
 111 {
 112     if (empty())
 113         return;
 114
 115     assert(_size >= fifo.begin()->packet->length);
 116     // Erase the packet at the head of the queue
 117     _size -= fifo.begin()->packet->length;
 118     fifo.erase(fifo.begin());
 119 }
 120
 121 void
 122 EtherSwitch::Interface::PortFifo::clear()
 123 {
 124     fifo.clear();
 125     _size = 0;
 126 }
 127
 128 EtherSwitch::Interface::Interface(const std::string &name,
 129                                   EtherSwitch *etherSwitch,
 130                                   uint64_t outputBufferSize, Tick delay,
 131                                   Tick delay_var, double rate, unsigned id)
 132     : EtherInt(name), ticksPerByte(rate), switchDelay(delay),
 133       delayVar(delay_var), interfaceId(id), parent(etherSwitch),
 134       outputFifo(name + ".outputFifo", outputBufferSize),
 135       txEvent([this]{ transmit(); }, name)
 136 {
 137 }
 138
 139 bool
 140 EtherSwitch::Interface::recvPacket(EthPacketPtr packet)
 141 {
 142     Net::EthAddr destMacAddr(packet->data);
 143     Net::EthAddr srcMacAddr(&packet->data[6]);
 144
 145     learnSenderAddr(srcMacAddr, this);
 146     Interface *receiver = lookupDestPort(destMacAddr);
 147
 148     if (!receiver || destMacAddr.multicast() || destMacAddr.broadcast()) {
 149         for (auto it : parent->interfaces)
 150             if (it != this)
 151                 it->enqueue(packet, interfaceId);
 152     } else {
 153         DPRINTF(Ethernet, "sending packet from MAC %x on port "
 154                 "%s to MAC %x on port %s\n", uint64_t(srcMacAddr),
 155                 this->name(), uint64_t(destMacAddr), receiver->name());
 156
 157         receiver->enqueue(packet, interfaceId);
 158     }
 159     // At the output port, we either have buffer space (no drop) or
 160     // don't (drop packet); in both cases packet is received on
 161     // the interface successfully and there is no notion of busy
 162     // interface here (as we don't have inputFifo)
 163     return true;
 164 }
 165
 166 void
 167 EtherSwitch::Interface::enqueue(EthPacketPtr packet, unsigned senderId)
 168 {
 169     // assuming per-interface transmission events,
 170     // if the newly push packet gets inserted at the head of the queue
 171     // (either there was nothing in the queue or the priority of the new
 172     // packet was higher than the packets already in the fifo)
 173     // then we need to schedule an event at
 174     // "curTick" + "switchingDelay of the packet at the head of the fifo"
 175     // to send this packet out the external link
 176     // otherwise, there is already a txEvent scheduled
 177     if (outputFifo.push(packet, senderId)) {
 178         parent->reschedule(txEvent, curTick() + switchingDelay(), true);
 179     }
 180 }
 181
 182 void
 183 EtherSwitch::Interface::transmit()
 184 {
 185     // there should be something in the output queue
 186     assert(!outputFifo.empty());
 187
 188     if (!sendPacket(outputFifo.front())) {
 189         DPRINTF(Ethernet, "output port busy...retry later\n");
 190         if (!txEvent.scheduled())
 191             parent->schedule(txEvent, curTick() + retryTime);
 192     } else {
 193         DPRINTF(Ethernet, "packet sent: len=%d\n", outputFifo.front()->length);
 194         outputFifo.pop();
 195         // schedule an event to send the pkt at
 196         // the head of queue, if there is any
 197         if (!outputFifo.empty()) {
 198             parent->schedule(txEvent, curTick() + switchingDelay());
 199         }
 200     }
 201 }
 202
 203 Tick
 204 EtherSwitch::Interface::switchingDelay()
 205 {
 206     Tick delay = (Tick)ceil(((double)outputFifo.front()->simLength
 207                                      * ticksPerByte) + 1.0);
 208     if (delayVar != 0)
 209                 delay += random_mt.random<Tick>(0, delayVar);
 210     delay += switchDelay;
 211     return delay;
 212 }
 213
 214 EtherSwitch::Interface*
 215 EtherSwitch::Interface::lookupDestPort(Net::EthAddr destMacAddr)
 216 {
 217     auto it = parent->forwardingTable.find(uint64_t(destMacAddr));
 218
 219     if (it == parent->forwardingTable.end()) {
 220         DPRINTF(Ethernet, "no entry in forwaring table for MAC: "
 221                 "%x\n", uint64_t(destMacAddr));
 222         return nullptr;
 223     }
 224
 225     // check if this entry is valid based on TTL and lastUseTime
 226     if ((curTick() - it->second.lastUseTime) > parent->ttl) {
 227         // TTL for this mapping has been expired, so this item is not
 228         // valide anymore, let's remove it from the map
 229         parent->forwardingTable.erase(it);
 230         return nullptr;
 231     }
 232
 233     DPRINTF(Ethernet, "found entry for MAC address %x on port %s\n",
 234             uint64_t(destMacAddr), it->second.interface->name());
 235     return it->second.interface;
 236 }
 237
 238 void
 239 EtherSwitch::Interface::learnSenderAddr(Net::EthAddr srcMacAddr,
 240                                           Interface *sender)
 241 {
 242     // learn the port for the sending MAC address
 243     auto it = parent->forwardingTable.find(uint64_t(srcMacAddr));
 244
 245     // if the port for sender's MAC address is not cached,
 246     // cache it now, otherwise just update lastUseTime time
 247     if (it == parent->forwardingTable.end()) {
 248         DPRINTF(Ethernet, "adding forwarding table entry for MAC "
 249                 " address %x on port %s\n", uint64_t(srcMacAddr),
 250                 sender->name());
 251         EtherSwitch::SwitchTableEntry forwardingTableEntry;
 252         forwardingTableEntry.interface = sender;
 253         forwardingTableEntry.lastUseTime = curTick();
 254         parent->forwardingTable.insert(std::make_pair(uint64_t(srcMacAddr),
 255             forwardingTableEntry));
 256     } else {
 257         it->second.lastUseTime = curTick();
 258     }
 259 }
 260
 261 void
 262 EtherSwitch::serialize(CheckpointOut &cp) const
 263 {
 264     for (auto it : interfaces)
 265         it->serializeSection(cp, it->name());
 266
 267 }
 268
 269 void
 270 EtherSwitch::unserialize(CheckpointIn &cp)
 271 {
 272     for (auto it : interfaces)
 273         it->unserializeSection(cp, it->name());
 274
 275 }
 276
 277 void
 278 EtherSwitch::Interface::serialize(CheckpointOut &cp) const
 279 {
 280     bool event_scheduled = txEvent.scheduled();
 281     SERIALIZE_SCALAR(event_scheduled);
 282
 283     if (event_scheduled) {
 284         Tick event_time = txEvent.when();
 285         SERIALIZE_SCALAR(event_time);
 286     }
 287     outputFifo.serializeSection(cp, "outputFifo");
 288 }
 289
 290 void
 291 EtherSwitch::Interface::unserialize(CheckpointIn &cp)
 292 {
 293     bool event_scheduled;
 294     UNSERIALIZE_SCALAR(event_scheduled);
 295
 296     if (event_scheduled) {
 297         Tick event_time;
 298         UNSERIALIZE_SCALAR(event_time);
 299         parent->schedule(txEvent, event_time);
 300     }
 301     outputFifo.unserializeSection(cp, "outputFifo");
 302 }
 303
 304 void
 305 EtherSwitch::Interface::PortFifoEntry::serialize(CheckpointOut &cp) const
 306 {
 307     packet->serialize("packet", cp);
 308     SERIALIZE_SCALAR(recvTick);
 309     SERIALIZE_SCALAR(srcId);
 310 }
 311
 312 void
 313 EtherSwitch::Interface::PortFifoEntry::unserialize(CheckpointIn &cp)
 314 {
 315     packet = make_shared<EthPacketData>(16384);
 316     packet->unserialize("packet", cp);
 317     UNSERIALIZE_SCALAR(recvTick);
 318     UNSERIALIZE_SCALAR(srcId);
 319 }
 320
 321 void
 322 EtherSwitch::Interface::PortFifo::serialize(CheckpointOut &cp) const
 323 {
 324     SERIALIZE_SCALAR(_size);
 325     int fifosize = fifo.size();
 326
 327     SERIALIZE_SCALAR(fifosize);
 328
 329     int i = 0;
 330     for (const auto &entry : fifo)
 331         entry.serializeSection(cp, csprintf("entry%d", i++));
 332 }
 333
 334 void
 335 EtherSwitch::Interface::PortFifo::unserialize(CheckpointIn &cp)
 336 {
 337     UNSERIALIZE_SCALAR(_size);
 338     int fifosize;
 339
 340     UNSERIALIZE_SCALAR(fifosize);
 341     fifo.clear();
 342
 343     for (int i = 0; i < fifosize; ++i) {
 344         PortFifoEntry entry(nullptr, 0, 0);
 345
 346         entry.unserializeSection(cp, csprintf("entry%d", i));
 347
 348         fifo.insert(entry);
 349
 350     }
 351 }
 352
 353 EtherSwitch *
 354 EtherSwitchParams::create()
 355 {
 356     return new EtherSwitch(this);
 357 }