4a453e8c95
This patch changes the packet queue such that when scheduling a send, the queue is allowed to move the event forward.
254 lines
8 KiB
C++
254 lines
8 KiB
C++
/*
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* Copyright (c) 2012 ARM Limited
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* All rights reserved.
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Copyright (c) 2006 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Ali Saidi
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* Andreas Hansson
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*/
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#include "base/trace.hh"
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#include "debug/Drain.hh"
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#include "debug/PacketQueue.hh"
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#include "mem/packet_queue.hh"
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using namespace std;
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PacketQueue::PacketQueue(EventManager& _em, const std::string& _label)
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: em(_em), sendEvent(this), drainManager(NULL), label(_label),
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waitingOnRetry(false)
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{
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}
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PacketQueue::~PacketQueue()
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{
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}
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void
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PacketQueue::retry()
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{
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DPRINTF(PacketQueue, "Queue %s received retry\n", name());
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assert(waitingOnRetry);
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sendDeferredPacket();
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}
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bool
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PacketQueue::checkFunctional(PacketPtr pkt)
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{
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pkt->pushLabel(label);
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auto i = transmitList.begin();
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bool found = false;
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while (!found && i != transmitList.end()) {
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// If the buffered packet contains data, and it overlaps the
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// current packet, then update data
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found = pkt->checkFunctional(i->pkt);
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++i;
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}
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pkt->popLabel();
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return found;
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}
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void
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PacketQueue::schedSendEvent(Tick when)
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{
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// if we are waiting on a retry, do not schedule a send event, and
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// instead rely on retry being called
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if (waitingOnRetry) {
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assert(!sendEvent.scheduled());
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return;
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}
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if (!sendEvent.scheduled()) {
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em.schedule(&sendEvent, when);
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} else if (sendEvent.when() > when) {
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em.reschedule(&sendEvent, when);
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}
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}
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void
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PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool send_as_snoop)
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{
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DPRINTF(PacketQueue, "%s for %s address %x size %d\n", __func__,
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pkt->cmdString(), pkt->getAddr(), pkt->getSize());
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// we can still send a packet before the end of this tick
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assert(when >= curTick());
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// express snoops should never be queued
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assert(!pkt->isExpressSnoop());
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// add a very basic sanity check on the port to ensure the
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// invisible buffer is not growing beyond reasonable limits
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if (transmitList.size() > 100) {
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panic("Packet queue %s has grown beyond 100 packets\n",
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name());
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}
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// nothing on the list, or earlier than current front element,
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// schedule an event
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if (transmitList.empty() || when < transmitList.front().tick) {
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// note that currently we ignore a potentially outstanding retry
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// and could in theory put a new packet at the head of the
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// transmit list before retrying the existing packet
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transmitList.push_front(DeferredPacket(when, pkt, send_as_snoop));
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schedSendEvent(when);
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return;
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}
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// list is non-empty and this belongs at the end
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if (when >= transmitList.back().tick) {
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transmitList.push_back(DeferredPacket(when, pkt, send_as_snoop));
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return;
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}
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// this belongs in the middle somewhere, insertion sort
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auto i = transmitList.begin();
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++i; // already checked for insertion at front
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while (i != transmitList.end() && when >= i->tick)
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++i;
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transmitList.insert(i, DeferredPacket(when, pkt, send_as_snoop));
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}
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void PacketQueue::trySendTiming()
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{
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assert(deferredPacketReady());
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DeferredPacket dp = transmitList.front();
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// use the appropriate implementation of sendTiming based on the
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// type of port associated with the queue, and whether the packet
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// is to be sent as a snoop or not
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waitingOnRetry = !sendTiming(dp.pkt, dp.sendAsSnoop);
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if (!waitingOnRetry) {
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// take the packet off the list
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transmitList.pop_front();
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}
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}
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void
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PacketQueue::scheduleSend(Tick time)
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{
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// the next ready time is either determined by the next deferred packet,
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// or in the cache through the MSHR ready time
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Tick nextReady = std::max(std::min(deferredPacketReadyTime(), time),
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curTick() + 1);
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if (nextReady != MaxTick) {
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// if the sendTiming caused someone else to call our
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// recvTiming we could already have an event scheduled, check
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if (!sendEvent.scheduled()) {
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em.schedule(&sendEvent, nextReady);
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} else if (nextReady < sendEvent.when()) {
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// if the new time is earlier than when the event
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// currently is scheduled, move it forward
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em.reschedule(&sendEvent, nextReady);
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}
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} else {
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// no more to send, so if we're draining, we may be done
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if (drainManager && transmitList.empty() && !sendEvent.scheduled()) {
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DPRINTF(Drain, "PacketQueue done draining,"
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"processing drain event\n");
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drainManager->signalDrainDone();
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drainManager = NULL;
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}
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}
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}
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void
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PacketQueue::sendDeferredPacket()
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{
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// try to send what is on the list, this will set waitingOnRetry
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// accordingly
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trySendTiming();
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// if we succeeded and are not waiting for a retry, schedule the
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// next send
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if (!waitingOnRetry) {
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scheduleSend();
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}
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}
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void
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PacketQueue::processSendEvent()
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{
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assert(!waitingOnRetry);
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sendDeferredPacket();
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}
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unsigned int
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PacketQueue::drain(DrainManager *dm)
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{
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if (transmitList.empty())
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return 0;
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DPRINTF(Drain, "PacketQueue not drained\n");
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drainManager = dm;
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return 1;
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}
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MasterPacketQueue::MasterPacketQueue(EventManager& _em, MasterPort& _masterPort,
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const std::string _label)
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: PacketQueue(_em, _label), masterPort(_masterPort)
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{
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}
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bool
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MasterPacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop)
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{
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// attempt to send the packet and return according to the outcome
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if (!send_as_snoop)
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return masterPort.sendTimingReq(pkt);
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else
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return masterPort.sendTimingSnoopResp(pkt);
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}
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SlavePacketQueue::SlavePacketQueue(EventManager& _em, SlavePort& _slavePort,
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const std::string _label)
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: PacketQueue(_em, _label), slavePort(_slavePort)
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{
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}
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bool
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SlavePacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop)
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{
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// we should never have queued snoop requests
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assert(!send_as_snoop);
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return slavePort.sendTimingResp(pkt);
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}
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