src/mem/packet_queue.cc - arm/gem5 - Git at Google

 /*
  * Copyright (c) 2012 ARM Limited
  * All rights reserved.
  *
  * The license below extends only to copyright in the software and shall
  * not be construed as granting a license to any other intellectual
  * property including but not limited to intellectual property relating
  * to a hardware implementation of the functionality of the software
  * licensed hereunder.  You may use the software subject to the license
  * terms below provided that you ensure that this notice is replicated
  * unmodified and in its entirety in all distributions of the software,
  * modified or unmodified, in source code or in binary form.
  *
  * Copyright (c) 2006 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.
  *
  * Authors: Ali Saidi
  *          Andreas Hansson
  */

 #include "base/trace.hh"
 #include "debug/Drain.hh"
 #include "debug/PacketQueue.hh"
 #include "mem/packet_queue.hh"

 using namespace std;

 PacketQueue::PacketQueue(EventManager& _em, const std::string& _label)
     : em(_em), sendEvent(this), drainManager(NULL), label(_label),
       waitingOnRetry(false)
 {
 }

 PacketQueue::~PacketQueue()
 {
 }

 void
 PacketQueue::retry()
 {
     DPRINTF(PacketQueue, "Queue %s received retry\n", name());
     assert(waitingOnRetry);
     sendDeferredPacket();
 }

 bool
 PacketQueue::checkFunctional(PacketPtr pkt)
 {
     pkt->pushLabel(label);

     auto i = transmitList.begin();
     bool found = false;

     while (!found && i != transmitList.end()) {
         // If the buffered packet contains data, and it overlaps the
         // current packet, then update data
         found = pkt->checkFunctional(i->pkt);
         ++i;
     }

     pkt->popLabel();

     return found;
 }

 void
 PacketQueue::schedSendEvent(Tick when)
 {
     // if we are waiting on a retry, do not schedule a send event, and
     // instead rely on retry being called
     if (waitingOnRetry) {
         assert(!sendEvent.scheduled());
         return;
     }

     if (!sendEvent.scheduled()) {
         em.schedule(&sendEvent, when);
     } else if (sendEvent.when() > when) {
         em.reschedule(&sendEvent, when);
     }
 }

 void
 PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool send_as_snoop)
 {
     DPRINTF(PacketQueue, "%s for %s address %x size %d\n", __func__,
             pkt->cmdString(), pkt->getAddr(), pkt->getSize());
     // we can still send a packet before the end of this tick
     assert(when >= curTick());

     // express snoops should never be queued
     assert(!pkt->isExpressSnoop());

     // add a very basic sanity check on the port to ensure the
     // invisible buffer is not growing beyond reasonable limits
     if (transmitList.size() > 100) {
         panic("Packet queue %s has grown beyond 100 packets\n",
               name());
     }

     // nothing on the list, or earlier than current front element,
     // schedule an event
     if (transmitList.empty() || when < transmitList.front().tick) {
         // note that currently we ignore a potentially outstanding retry
         // and could in theory put a new packet at the head of the
         // transmit list before retrying the existing packet
         transmitList.push_front(DeferredPacket(when, pkt, send_as_snoop));
         schedSendEvent(when);
         return;
     }

     // list is non-empty and this belongs at the end
     if (when >= transmitList.back().tick) {
         transmitList.push_back(DeferredPacket(when, pkt, send_as_snoop));
         return;
     }

     // this belongs in the middle somewhere, insertion sort
     auto i = transmitList.begin();
     ++i; // already checked for insertion at front
     while (i != transmitList.end() && when >= i->tick)
         ++i;
     transmitList.insert(i, DeferredPacket(when, pkt, send_as_snoop));
 }

 void PacketQueue::trySendTiming()
 {
     assert(deferredPacketReady());

     DeferredPacket dp = transmitList.front();

     // use the appropriate implementation of sendTiming based on the
     // type of port associated with the queue, and whether the packet
     // is to be sent as a snoop or not
     waitingOnRetry = !sendTiming(dp.pkt, dp.sendAsSnoop);

     if (!waitingOnRetry) {
         // take the packet off the list
         transmitList.pop_front();
     }
 }

 void
 PacketQueue::scheduleSend(Tick time)
 {
     // the next ready time is either determined by the next deferred packet,
     // or in the cache through the MSHR ready time
     Tick nextReady = std::max(std::min(deferredPacketReadyTime(), time),
                               curTick() + 1);

     if (nextReady != MaxTick) {
         // if the sendTiming caused someone else to call our
         // recvTiming we could already have an event scheduled, check
         if (!sendEvent.scheduled()) {
             em.schedule(&sendEvent, nextReady);
         } else if (nextReady < sendEvent.when()) {
             // if the new time is earlier than when the event
             // currently is scheduled, move it forward
             em.reschedule(&sendEvent, nextReady);
         }
     } else {
         // no more to send, so if we're draining, we may be done
         if (drainManager && transmitList.empty() && !sendEvent.scheduled()) {
             DPRINTF(Drain, "PacketQueue done draining,"
                     "processing drain event\n");
             drainManager->signalDrainDone();
             drainManager = NULL;
         }
     }
 }

 void
 PacketQueue::sendDeferredPacket()
 {
     // try to send what is on the list, this will set waitingOnRetry
     // accordingly
     trySendTiming();

     // if we succeeded and are not waiting for a retry, schedule the
     // next send
     if (!waitingOnRetry) {
         scheduleSend();
     }
 }

 void
 PacketQueue::processSendEvent()
 {
     assert(!waitingOnRetry);
     sendDeferredPacket();
 }

 unsigned int
 PacketQueue::drain(DrainManager *dm)
 {
     if (transmitList.empty())
         return 0;
     DPRINTF(Drain, "PacketQueue not drained\n");
     drainManager = dm;
     return 1;
 }

 MasterPacketQueue::MasterPacketQueue(EventManager& _em, MasterPort& _masterPort,
                                      const std::string _label)
     : PacketQueue(_em, _label), masterPort(_masterPort)
 {
 }

 bool
 MasterPacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop)
 {
     // attempt to send the packet and return according to the outcome
     if (!send_as_snoop)
         return masterPort.sendTimingReq(pkt);
     else
         return masterPort.sendTimingSnoopResp(pkt);
 }

 SlavePacketQueue::SlavePacketQueue(EventManager& _em, SlavePort& _slavePort,
                                    const std::string _label)
     : PacketQueue(_em, _label), slavePort(_slavePort)
 {
 }

 bool
 SlavePacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop)
 {
     // we should never have queued snoop requests
     assert(!send_as_snoop);
     return slavePort.sendTimingResp(pkt);
 }
	/*
	* Copyright (c) 2012 ARM Limited
	* All rights reserved.
	*
	* The license below extends only to copyright in the software and shall
	* not be construed as granting a license to any other intellectual
	* property including but not limited to intellectual property relating
	* to a hardware implementation of the functionality of the software
	* licensed hereunder. You may use the software subject to the license
	* terms below provided that you ensure that this notice is replicated
	* unmodified and in its entirety in all distributions of the software,
	* modified or unmodified, in source code or in binary form.
	*
	* Copyright (c) 2006 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.
	*
	* Authors: Ali Saidi
	* Andreas Hansson
	*/

	#include "base/trace.hh"
	#include "debug/Drain.hh"
	#include "debug/PacketQueue.hh"
	#include "mem/packet_queue.hh"

	using namespace std;

	PacketQueue::PacketQueue(EventManager& _em, const std::string& _label)
	: em(_em), sendEvent(this), drainManager(NULL), label(_label),
	waitingOnRetry(false)
	{
	}

	PacketQueue::~PacketQueue()
	{
	}

	void
	PacketQueue::retry()
	{
	DPRINTF(PacketQueue, "Queue %s received retry\n", name());
	assert(waitingOnRetry);
	sendDeferredPacket();
	}

	bool
	PacketQueue::checkFunctional(PacketPtr pkt)
	{
	pkt->pushLabel(label);

	auto i = transmitList.begin();
	bool found = false;

	while (!found && i != transmitList.end()) {
	// If the buffered packet contains data, and it overlaps the
	// current packet, then update data
	found = pkt->checkFunctional(i->pkt);
	++i;
	}

	pkt->popLabel();

	return found;
	}

	void
	PacketQueue::schedSendEvent(Tick when)
	{
	// if we are waiting on a retry, do not schedule a send event, and
	// instead rely on retry being called
	if (waitingOnRetry) {
	assert(!sendEvent.scheduled());
	return;
	}

	if (!sendEvent.scheduled()) {
	em.schedule(&sendEvent, when);
	} else if (sendEvent.when() > when) {
	em.reschedule(&sendEvent, when);
	}
	}

	void
	PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool send_as_snoop)
	{
	DPRINTF(PacketQueue, "%s for %s address %x size %d\n", __func__,
	pkt->cmdString(), pkt->getAddr(), pkt->getSize());
	// we can still send a packet before the end of this tick
	assert(when >= curTick());

	// express snoops should never be queued
	assert(!pkt->isExpressSnoop());

	// add a very basic sanity check on the port to ensure the
	// invisible buffer is not growing beyond reasonable limits
	if (transmitList.size() > 100) {
	panic("Packet queue %s has grown beyond 100 packets\n",
	name());
	}

	// nothing on the list, or earlier than current front element,
	// schedule an event
	if (transmitList.empty() \|\| when < transmitList.front().tick) {
	// note that currently we ignore a potentially outstanding retry
	// and could in theory put a new packet at the head of the
	// transmit list before retrying the existing packet
	transmitList.push_front(DeferredPacket(when, pkt, send_as_snoop));
	schedSendEvent(when);
	return;
	}

	// list is non-empty and this belongs at the end
	if (when >= transmitList.back().tick) {
	transmitList.push_back(DeferredPacket(when, pkt, send_as_snoop));
	return;
	}

	// this belongs in the middle somewhere, insertion sort
	auto i = transmitList.begin();
	++i; // already checked for insertion at front
	while (i != transmitList.end() && when >= i->tick)
	++i;
	transmitList.insert(i, DeferredPacket(when, pkt, send_as_snoop));
	}

	void PacketQueue::trySendTiming()
	{
	assert(deferredPacketReady());

	DeferredPacket dp = transmitList.front();

	// use the appropriate implementation of sendTiming based on the
	// type of port associated with the queue, and whether the packet
	// is to be sent as a snoop or not
	waitingOnRetry = !sendTiming(dp.pkt, dp.sendAsSnoop);

	if (!waitingOnRetry) {
	// take the packet off the list
	transmitList.pop_front();
	}
	}

	void
	PacketQueue::scheduleSend(Tick time)
	{
	// the next ready time is either determined by the next deferred packet,
	// or in the cache through the MSHR ready time
	Tick nextReady = std::max(std::min(deferredPacketReadyTime(), time),
	curTick() + 1);

	if (nextReady != MaxTick) {
	// if the sendTiming caused someone else to call our
	// recvTiming we could already have an event scheduled, check
	if (!sendEvent.scheduled()) {
	em.schedule(&sendEvent, nextReady);
	} else if (nextReady < sendEvent.when()) {
	// if the new time is earlier than when the event
	// currently is scheduled, move it forward
	em.reschedule(&sendEvent, nextReady);
	}
	} else {
	// no more to send, so if we're draining, we may be done
	if (drainManager && transmitList.empty() && !sendEvent.scheduled()) {
	DPRINTF(Drain, "PacketQueue done draining,"
	"processing drain event\n");
	drainManager->signalDrainDone();
	drainManager = NULL;
	}
	}
	}

	void
	PacketQueue::sendDeferredPacket()
	{
	// try to send what is on the list, this will set waitingOnRetry
	// accordingly
	trySendTiming();

	// if we succeeded and are not waiting for a retry, schedule the
	// next send
	if (!waitingOnRetry) {
	scheduleSend();
	}
	}

	void
	PacketQueue::processSendEvent()
	{
	assert(!waitingOnRetry);
	sendDeferredPacket();
	}

	unsigned int
	PacketQueue::drain(DrainManager *dm)
	{
	if (transmitList.empty())
	return 0;
	DPRINTF(Drain, "PacketQueue not drained\n");
	drainManager = dm;
	return 1;
	}

	MasterPacketQueue::MasterPacketQueue(EventManager& _em, MasterPort& _masterPort,
	const std::string _label)
	: PacketQueue(_em, _label), masterPort(_masterPort)
	{
	}

	bool
	MasterPacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop)
	{
	// attempt to send the packet and return according to the outcome
	if (!send_as_snoop)
	return masterPort.sendTimingReq(pkt);
	else
	return masterPort.sendTimingSnoopResp(pkt);
	}

	SlavePacketQueue::SlavePacketQueue(EventManager& _em, SlavePort& _slavePort,
	const std::string _label)
	: PacketQueue(_em, _label), slavePort(_slavePort)
	{
	}

	bool
	SlavePacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop)
	{
	// we should never have queued snoop requests
	assert(!send_as_snoop);
	return slavePort.sendTimingResp(pkt);
	}