src/dev/net/etherswitch.cc - public/gem5 - Git at Google

 /*
  * Copyright (c) 2014 The Regents of The University of Michigan
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 /* @file
  * Device model for an ethernet switch
  */

 #include "dev/net/etherswitch.hh"

 #include "base/random.hh"
 #include "base/trace.hh"
 #include "debug/EthernetAll.hh"
 #include "sim/core.hh"

 using namespace std;

 EtherSwitch::EtherSwitch(const Params *p)
     : SimObject(p), ttl(p->time_to_live)
 {
     for (int i = 0; i < p->port_interface_connection_count; ++i) {
         std::string interfaceName = csprintf("%s.interface%d", name(), i);
         Interface *interface = new Interface(interfaceName, this,
                                         p->output_buffer_size, p->delay,
                                         p->delay_var, p->fabric_speed, i);
         interfaces.push_back(interface);
     }
 }

 EtherSwitch::~EtherSwitch()
 {
     for (auto it : interfaces)
         delete it;

     interfaces.clear();
 }

 Port &
 EtherSwitch::getPort(const std::string &if_name, PortID idx)
 {
     if (if_name == "interface") {
         panic_if(idx < 0 || idx >= interfaces.size(), "index out of bounds");
         return *interfaces.at(idx);
     }

     return SimObject::getPort(if_name, idx);
 }

 bool
 EtherSwitch::Interface::PortFifo::push(EthPacketPtr ptr, unsigned senderId)
 {
     assert(ptr->length);

     _size += ptr->length;
     fifo.emplace_hint(fifo.end(), ptr, curTick(), senderId);

     // Drop the extra pushed packets from end of the fifo
     while (avail() < 0) {
         DPRINTF(Ethernet, "Fifo is full. Drop packet: len=%d\n",
                 std::prev(fifo.end())->packet->length);

         _size -= std::prev(fifo.end())->packet->length;
         fifo.erase(std::prev(fifo.end()));
     }

     if (empty()) {
         warn("EtherSwitch: Packet length (%d) exceeds the maximum storage "
              "capacity of port fifo (%d)", ptr->length, _maxsize);
     }

     // Return true if the newly pushed packet gets inserted
     // at the head of the queue, otherwise return false
     // We need this information to deschedule the event that has been
     // scheduled for the old head of queue packet and schedule a new one
     if (!empty() && fifo.begin()->packet == ptr) {
         return true;
     }
     return false;
 }

 void
 EtherSwitch::Interface::PortFifo::pop()
 {
     if (empty())
         return;

     assert(_size >= fifo.begin()->packet->length);
     // Erase the packet at the head of the queue
     _size -= fifo.begin()->packet->length;
     fifo.erase(fifo.begin());
 }

 void
 EtherSwitch::Interface::PortFifo::clear()
 {
     fifo.clear();
     _size = 0;
 }

 EtherSwitch::Interface::Interface(const std::string &name,
                                   EtherSwitch *etherSwitch,
                                   uint64_t outputBufferSize, Tick delay,
                                   Tick delay_var, double rate, unsigned id)
     : EtherInt(name), ticksPerByte(rate), switchDelay(delay),
       delayVar(delay_var), interfaceId(id), parent(etherSwitch),
       outputFifo(name + ".outputFifo", outputBufferSize),
       txEvent([this]{ transmit(); }, name)
 {
 }

 bool
 EtherSwitch::Interface::recvPacket(EthPacketPtr packet)
 {
     Net::EthAddr destMacAddr(packet->data);
     Net::EthAddr srcMacAddr(&packet->data[6]);

     learnSenderAddr(srcMacAddr, this);
     Interface *receiver = lookupDestPort(destMacAddr);

     if (!receiver || destMacAddr.multicast() || destMacAddr.broadcast()) {
         for (auto it : parent->interfaces)
             if (it != this)
                 it->enqueue(packet, interfaceId);
     } else {
         DPRINTF(Ethernet, "sending packet from MAC %x on port "
                 "%s to MAC %x on port %s\n", uint64_t(srcMacAddr),
                 this->name(), uint64_t(destMacAddr), receiver->name());

         receiver->enqueue(packet, interfaceId);
     }
     // At the output port, we either have buffer space (no drop) or
     // don't (drop packet); in both cases packet is received on
     // the interface successfully and there is no notion of busy
     // interface here (as we don't have inputFifo)
     return true;
 }

 void
 EtherSwitch::Interface::enqueue(EthPacketPtr packet, unsigned senderId)
 {
     // assuming per-interface transmission events,
     // if the newly push packet gets inserted at the head of the queue
     // (either there was nothing in the queue or the priority of the new
     // packet was higher than the packets already in the fifo)
     // then we need to schedule an event at
     // "curTick" + "switchingDelay of the packet at the head of the fifo"
     // to send this packet out the external link
     // otherwise, there is already a txEvent scheduled
     if (outputFifo.push(packet, senderId)) {
         parent->reschedule(txEvent, curTick() + switchingDelay(), true);
     }
 }

 void
 EtherSwitch::Interface::transmit()
 {
     // there should be something in the output queue
     assert(!outputFifo.empty());

     if (!sendPacket(outputFifo.front())) {
         DPRINTF(Ethernet, "output port busy...retry later\n");
         if (!txEvent.scheduled())
             parent->schedule(txEvent, curTick() + SimClock::Int::ns);
     } else {
         DPRINTF(Ethernet, "packet sent: len=%d\n", outputFifo.front()->length);
         outputFifo.pop();
         // schedule an event to send the pkt at
         // the head of queue, if there is any
         if (!outputFifo.empty()) {
             parent->schedule(txEvent, curTick() + switchingDelay());
         }
     }
 }

 Tick
 EtherSwitch::Interface::switchingDelay()
 {
     Tick delay = (Tick)ceil(((double)outputFifo.front()->simLength
                                      * ticksPerByte) + 1.0);
     if (delayVar != 0)
                 delay += random_mt.random<Tick>(0, delayVar);
     delay += switchDelay;
     return delay;
 }

 EtherSwitch::Interface*
 EtherSwitch::Interface::lookupDestPort(Net::EthAddr destMacAddr)
 {
     auto it = parent->forwardingTable.find(uint64_t(destMacAddr));

     if (it == parent->forwardingTable.end()) {
         DPRINTF(Ethernet, "no entry in forwaring table for MAC: "
                 "%x\n", uint64_t(destMacAddr));
         return nullptr;
     }

     // check if this entry is valid based on TTL and lastUseTime
     if ((curTick() - it->second.lastUseTime) > parent->ttl) {
         // TTL for this mapping has been expired, so this item is not
         // valide anymore, let's remove it from the map
         parent->forwardingTable.erase(it);
         return nullptr;
     }

     DPRINTF(Ethernet, "found entry for MAC address %x on port %s\n",
             uint64_t(destMacAddr), it->second.interface->name());
     return it->second.interface;
 }

 void
 EtherSwitch::Interface::learnSenderAddr(Net::EthAddr srcMacAddr,
                                           Interface *sender)
 {
     // learn the port for the sending MAC address
     auto it = parent->forwardingTable.find(uint64_t(srcMacAddr));

     // if the port for sender's MAC address is not cached,
     // cache it now, otherwise just update lastUseTime time
     if (it == parent->forwardingTable.end()) {
         DPRINTF(Ethernet, "adding forwarding table entry for MAC "
                 " address %x on port %s\n", uint64_t(srcMacAddr),
                 sender->name());
         EtherSwitch::SwitchTableEntry forwardingTableEntry;
         forwardingTableEntry.interface = sender;
         forwardingTableEntry.lastUseTime = curTick();
         parent->forwardingTable.insert(std::make_pair(uint64_t(srcMacAddr),
             forwardingTableEntry));
     } else {
         it->second.lastUseTime = curTick();
     }
 }

 void
 EtherSwitch::serialize(CheckpointOut &cp) const
 {
     for (auto it : interfaces)
         it->serializeSection(cp, it->name());

 }

 void
 EtherSwitch::unserialize(CheckpointIn &cp)
 {
     for (auto it : interfaces)
         it->unserializeSection(cp, it->name());

 }

 void
 EtherSwitch::Interface::serialize(CheckpointOut &cp) const
 {
     bool event_scheduled = txEvent.scheduled();
     SERIALIZE_SCALAR(event_scheduled);

     if (event_scheduled) {
         Tick event_time = txEvent.when();
         SERIALIZE_SCALAR(event_time);
     }
     outputFifo.serializeSection(cp, "outputFifo");
 }

 void
 EtherSwitch::Interface::unserialize(CheckpointIn &cp)
 {
     bool event_scheduled;
     UNSERIALIZE_SCALAR(event_scheduled);

     if (event_scheduled) {
         Tick event_time;
         UNSERIALIZE_SCALAR(event_time);
         parent->schedule(txEvent, event_time);
     }
     outputFifo.unserializeSection(cp, "outputFifo");
 }

 void
 EtherSwitch::Interface::PortFifoEntry::serialize(CheckpointOut &cp) const
 {
     packet->serialize("packet", cp);
     SERIALIZE_SCALAR(recvTick);
     SERIALIZE_SCALAR(srcId);
 }

 void
 EtherSwitch::Interface::PortFifoEntry::unserialize(CheckpointIn &cp)
 {
     packet = make_shared<EthPacketData>(16384);
     packet->unserialize("packet", cp);
     UNSERIALIZE_SCALAR(recvTick);
     UNSERIALIZE_SCALAR(srcId);
 }

 void
 EtherSwitch::Interface::PortFifo::serialize(CheckpointOut &cp) const
 {
     SERIALIZE_SCALAR(_size);
     int fifosize = fifo.size();

     SERIALIZE_SCALAR(fifosize);

     int i = 0;
     for (const auto &entry : fifo)
         entry.serializeSection(cp, csprintf("entry%d", i++));
 }

 void
 EtherSwitch::Interface::PortFifo::unserialize(CheckpointIn &cp)
 {
     UNSERIALIZE_SCALAR(_size);
     int fifosize;

     UNSERIALIZE_SCALAR(fifosize);
     fifo.clear();

     for (int i = 0; i < fifosize; ++i) {
         PortFifoEntry entry(nullptr, 0, 0);

         entry.unserializeSection(cp, csprintf("entry%d", i));

         fifo.insert(entry);

     }
 }

 EtherSwitch *
 EtherSwitchParams::create()
 {
     return new EtherSwitch(this);
 }
	/*
	* Copyright (c) 2014 The Regents of The University of Michigan
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	/* @file
	* Device model for an ethernet switch
	*/

	#include "dev/net/etherswitch.hh"

	#include "base/random.hh"
	#include "base/trace.hh"
	#include "debug/EthernetAll.hh"
	#include "sim/core.hh"

	using namespace std;

	EtherSwitch::EtherSwitch(const Params *p)
	: SimObject(p), ttl(p->time_to_live)
	{
	for (int i = 0; i < p->port_interface_connection_count; ++i) {
	std::string interfaceName = csprintf("%s.interface%d", name(), i);
	Interface *interface = new Interface(interfaceName, this,
	p->output_buffer_size, p->delay,
	p->delay_var, p->fabric_speed, i);
	interfaces.push_back(interface);
	}
	}

	EtherSwitch::~EtherSwitch()
	{
	for (auto it : interfaces)
	delete it;

	interfaces.clear();
	}

	Port &
	EtherSwitch::getPort(const std::string &if_name, PortID idx)
	{
	if (if_name == "interface") {
	panic_if(idx < 0 \|\| idx >= interfaces.size(), "index out of bounds");
	return *interfaces.at(idx);
	}

	return SimObject::getPort(if_name, idx);
	}

	bool
	EtherSwitch::Interface::PortFifo::push(EthPacketPtr ptr, unsigned senderId)
	{
	assert(ptr->length);

	_size += ptr->length;
	fifo.emplace_hint(fifo.end(), ptr, curTick(), senderId);

	// Drop the extra pushed packets from end of the fifo
	while (avail() < 0) {
	DPRINTF(Ethernet, "Fifo is full. Drop packet: len=%d\n",
	std::prev(fifo.end())->packet->length);

	_size -= std::prev(fifo.end())->packet->length;
	fifo.erase(std::prev(fifo.end()));
	}

	if (empty()) {
	warn("EtherSwitch: Packet length (%d) exceeds the maximum storage "
	"capacity of port fifo (%d)", ptr->length, _maxsize);
	}

	// Return true if the newly pushed packet gets inserted
	// at the head of the queue, otherwise return false
	// We need this information to deschedule the event that has been
	// scheduled for the old head of queue packet and schedule a new one
	if (!empty() && fifo.begin()->packet == ptr) {
	return true;
	}
	return false;
	}

	void
	EtherSwitch::Interface::PortFifo::pop()
	{
	if (empty())
	return;

	assert(_size >= fifo.begin()->packet->length);
	// Erase the packet at the head of the queue
	_size -= fifo.begin()->packet->length;
	fifo.erase(fifo.begin());
	}

	void
	EtherSwitch::Interface::PortFifo::clear()
	{
	fifo.clear();
	_size = 0;
	}

	EtherSwitch::Interface::Interface(const std::string &name,
	EtherSwitch *etherSwitch,
	uint64_t outputBufferSize, Tick delay,
	Tick delay_var, double rate, unsigned id)
	: EtherInt(name), ticksPerByte(rate), switchDelay(delay),
	delayVar(delay_var), interfaceId(id), parent(etherSwitch),
	outputFifo(name + ".outputFifo", outputBufferSize),
	txEvent([this]{ transmit(); }, name)
	{
	}

	bool
	EtherSwitch::Interface::recvPacket(EthPacketPtr packet)
	{
	Net::EthAddr destMacAddr(packet->data);
	Net::EthAddr srcMacAddr(&packet->data[6]);

	learnSenderAddr(srcMacAddr, this);
	Interface *receiver = lookupDestPort(destMacAddr);

	if (!receiver \|\| destMacAddr.multicast() \|\| destMacAddr.broadcast()) {
	for (auto it : parent->interfaces)
	if (it != this)
	it->enqueue(packet, interfaceId);
	} else {
	DPRINTF(Ethernet, "sending packet from MAC %x on port "
	"%s to MAC %x on port %s\n", uint64_t(srcMacAddr),
	this->name(), uint64_t(destMacAddr), receiver->name());

	receiver->enqueue(packet, interfaceId);
	}
	// At the output port, we either have buffer space (no drop) or
	// don't (drop packet); in both cases packet is received on
	// the interface successfully and there is no notion of busy
	// interface here (as we don't have inputFifo)
	return true;
	}

	void
	EtherSwitch::Interface::enqueue(EthPacketPtr packet, unsigned senderId)
	{
	// assuming per-interface transmission events,
	// if the newly push packet gets inserted at the head of the queue
	// (either there was nothing in the queue or the priority of the new
	// packet was higher than the packets already in the fifo)
	// then we need to schedule an event at
	// "curTick" + "switchingDelay of the packet at the head of the fifo"
	// to send this packet out the external link
	// otherwise, there is already a txEvent scheduled
	if (outputFifo.push(packet, senderId)) {
	parent->reschedule(txEvent, curTick() + switchingDelay(), true);
	}
	}

	void
	EtherSwitch::Interface::transmit()
	{
	// there should be something in the output queue
	assert(!outputFifo.empty());

	if (!sendPacket(outputFifo.front())) {
	DPRINTF(Ethernet, "output port busy...retry later\n");
	if (!txEvent.scheduled())
	parent->schedule(txEvent, curTick() + SimClock::Int::ns);
	} else {
	DPRINTF(Ethernet, "packet sent: len=%d\n", outputFifo.front()->length);
	outputFifo.pop();
	// schedule an event to send the pkt at
	// the head of queue, if there is any
	if (!outputFifo.empty()) {
	parent->schedule(txEvent, curTick() + switchingDelay());
	}
	}
	}

	Tick
	EtherSwitch::Interface::switchingDelay()
	{
	Tick delay = (Tick)ceil(((double)outputFifo.front()->simLength
	* ticksPerByte) + 1.0);
	if (delayVar != 0)
	delay += random_mt.random<Tick>(0, delayVar);
	delay += switchDelay;
	return delay;
	}

	EtherSwitch::Interface*
	EtherSwitch::Interface::lookupDestPort(Net::EthAddr destMacAddr)
	{
	auto it = parent->forwardingTable.find(uint64_t(destMacAddr));

	if (it == parent->forwardingTable.end()) {
	DPRINTF(Ethernet, "no entry in forwaring table for MAC: "
	"%x\n", uint64_t(destMacAddr));
	return nullptr;
	}

	// check if this entry is valid based on TTL and lastUseTime
	if ((curTick() - it->second.lastUseTime) > parent->ttl) {
	// TTL for this mapping has been expired, so this item is not
	// valide anymore, let's remove it from the map
	parent->forwardingTable.erase(it);
	return nullptr;
	}

	DPRINTF(Ethernet, "found entry for MAC address %x on port %s\n",
	uint64_t(destMacAddr), it->second.interface->name());
	return it->second.interface;
	}

	void
	EtherSwitch::Interface::learnSenderAddr(Net::EthAddr srcMacAddr,
	Interface *sender)
	{
	// learn the port for the sending MAC address
	auto it = parent->forwardingTable.find(uint64_t(srcMacAddr));

	// if the port for sender's MAC address is not cached,
	// cache it now, otherwise just update lastUseTime time
	if (it == parent->forwardingTable.end()) {
	DPRINTF(Ethernet, "adding forwarding table entry for MAC "
	" address %x on port %s\n", uint64_t(srcMacAddr),
	sender->name());
	EtherSwitch::SwitchTableEntry forwardingTableEntry;
	forwardingTableEntry.interface = sender;
	forwardingTableEntry.lastUseTime = curTick();
	parent->forwardingTable.insert(std::make_pair(uint64_t(srcMacAddr),
	forwardingTableEntry));
	} else {
	it->second.lastUseTime = curTick();
	}
	}

	void
	EtherSwitch::serialize(CheckpointOut &cp) const
	{
	for (auto it : interfaces)
	it->serializeSection(cp, it->name());

	}

	void
	EtherSwitch::unserialize(CheckpointIn &cp)
	{
	for (auto it : interfaces)
	it->unserializeSection(cp, it->name());

	}

	void
	EtherSwitch::Interface::serialize(CheckpointOut &cp) const
	{
	bool event_scheduled = txEvent.scheduled();
	SERIALIZE_SCALAR(event_scheduled);

	if (event_scheduled) {
	Tick event_time = txEvent.when();
	SERIALIZE_SCALAR(event_time);
	}
	outputFifo.serializeSection(cp, "outputFifo");
	}

	void
	EtherSwitch::Interface::unserialize(CheckpointIn &cp)
	{
	bool event_scheduled;
	UNSERIALIZE_SCALAR(event_scheduled);

	if (event_scheduled) {
	Tick event_time;
	UNSERIALIZE_SCALAR(event_time);
	parent->schedule(txEvent, event_time);
	}
	outputFifo.unserializeSection(cp, "outputFifo");
	}

	void
	EtherSwitch::Interface::PortFifoEntry::serialize(CheckpointOut &cp) const
	{
	packet->serialize("packet", cp);
	SERIALIZE_SCALAR(recvTick);
	SERIALIZE_SCALAR(srcId);
	}

	void
	EtherSwitch::Interface::PortFifoEntry::unserialize(CheckpointIn &cp)
	{
	packet = make_shared<EthPacketData>(16384);
	packet->unserialize("packet", cp);
	UNSERIALIZE_SCALAR(recvTick);
	UNSERIALIZE_SCALAR(srcId);
	}

	void
	EtherSwitch::Interface::PortFifo::serialize(CheckpointOut &cp) const
	{
	SERIALIZE_SCALAR(_size);
	int fifosize = fifo.size();

	SERIALIZE_SCALAR(fifosize);

	int i = 0;
	for (const auto &entry : fifo)
	entry.serializeSection(cp, csprintf("entry%d", i++));
	}

	void
	EtherSwitch::Interface::PortFifo::unserialize(CheckpointIn &cp)
	{
	UNSERIALIZE_SCALAR(_size);
	int fifosize;

	UNSERIALIZE_SCALAR(fifosize);
	fifo.clear();

	for (int i = 0; i < fifosize; ++i) {
	PortFifoEntry entry(nullptr, 0, 0);

	entry.unserializeSection(cp, csprintf("entry%d", i));

	fifo.insert(entry);

	}
	}

	EtherSwitch *
	EtherSwitchParams::create()
	{
	return new EtherSwitch(this);
	}