packet_queue.cc revision 8948
1/* 2 * Copyright (c) 2012 ARM Limited 3 * All rights reserved. 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2006 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Ali Saidi 41 * Andreas Hansson 42 */ 43 44#include "debug/PacketQueue.hh" 45#include "mem/packet_queue.hh" 46 47using namespace std; 48 49PacketQueue::PacketQueue(EventManager& _em, Port& _port, 50 const std::string _label) 51 : em(_em), label(_label), sendEvent(this), drainEvent(NULL), port(_port), 52 waitingOnRetry(false) 53{ 54} 55 56PacketQueue::~PacketQueue() 57{ 58} 59 60void 61PacketQueue::retry() 62{ 63 DPRINTF(PacketQueue, "Queue %s received retry\n", name()); 64 assert(waitingOnRetry); 65 sendDeferredPacket(); 66} 67 68bool 69PacketQueue::checkFunctional(PacketPtr pkt) 70{ 71 pkt->pushLabel(label); 72 73 DeferredPacketIterator i = transmitList.begin(); 74 DeferredPacketIterator end = transmitList.end(); 75 bool found = false; 76 77 while (!found && i != end) { 78 // If the buffered packet contains data, and it overlaps the 79 // current packet, then update data 80 found = pkt->checkFunctional(i->pkt); 81 ++i; 82 } 83 84 pkt->popLabel(); 85 86 return found; 87} 88 89void 90PacketQueue::schedSendEvent(Tick when) 91{ 92 // if we are waiting on a retry, do not schedule a send event, and 93 // instead rely on retry being called 94 if (waitingOnRetry) { 95 assert(!sendEvent.scheduled()); 96 return; 97 } 98 99 if (!sendEvent.scheduled()) { 100 em.schedule(&sendEvent, when); 101 } else if (sendEvent.when() > when) { 102 em.reschedule(&sendEvent, when); 103 } 104} 105 106void 107PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool send_as_snoop) 108{ 109 assert(when > curTick()); 110 111 // nothing on the list, or earlier than current front element, 112 // schedule an event 113 if (transmitList.empty() || when < transmitList.front().tick) { 114 // note that currently we ignore a potentially outstanding retry 115 // and could in theory put a new packet at the head of the 116 // transmit list before retrying the existing packet 117 transmitList.push_front(DeferredPacket(when, pkt, send_as_snoop)); 118 schedSendEvent(when); 119 return; 120 } 121 122 // list is non-empty and this belongs at the end 123 if (when >= transmitList.back().tick) { 124 transmitList.push_back(DeferredPacket(when, pkt, send_as_snoop)); 125 return; 126 } 127 128 // this belongs in the middle somewhere, insertion sort 129 DeferredPacketIterator i = transmitList.begin(); 130 ++i; // already checked for insertion at front 131 while (i != transmitList.end() && when >= i->tick) 132 ++i; 133 transmitList.insert(i, DeferredPacket(when, pkt, send_as_snoop)); 134} 135 136void PacketQueue::trySendTiming() 137{ 138 assert(deferredPacketReady()); 139 140 // take the next packet off the list here, as we might return to 141 // ourselves through the sendTiming call below 142 DeferredPacket dp = transmitList.front(); 143 transmitList.pop_front(); 144 145 // attempt to send the packet and remember the outcome 146 if (!dp.sendAsSnoop) 147 waitingOnRetry = !port.sendTiming(dp.pkt); 148 else 149 waitingOnRetry = !port.sendTimingSnoop(dp.pkt); 150 151 if (waitingOnRetry) { 152 // put the packet back at the front of the list (packet should 153 // not have changed since it wasn't accepted) 154 assert(!sendEvent.scheduled()); 155 transmitList.push_front(dp); 156 } 157} 158 159void 160PacketQueue::scheduleSend(Tick time) 161{ 162 // the next ready time is either determined by the next deferred packet, 163 // or in the cache through the MSHR ready time 164 Tick nextReady = std::min(deferredPacketReadyTime(), time); 165 166 if (nextReady != MaxTick) { 167 // if the sendTiming caused someone else to call our 168 // recvTiming we could already have an event scheduled, check 169 if (!sendEvent.scheduled()) 170 em.schedule(&sendEvent, std::max(nextReady, curTick() + 1)); 171 } else { 172 // no more to send, so if we're draining, we may be done 173 if (drainEvent && !sendEvent.scheduled()) { 174 drainEvent->process(); 175 drainEvent = NULL; 176 } 177 } 178} 179 180void 181PacketQueue::sendDeferredPacket() 182{ 183 // try to send what is on the list, this will set waitingOnRetry 184 // accordingly 185 trySendTiming(); 186 187 // if we succeeded and are not waiting for a retry, schedule the 188 // next send 189 if (!waitingOnRetry) { 190 scheduleSend(); 191 } 192} 193 194void 195PacketQueue::processSendEvent() 196{ 197 assert(!waitingOnRetry); 198 sendDeferredPacket(); 199} 200 201unsigned int 202PacketQueue::drain(Event *de) 203{ 204 if (transmitList.empty() && !sendEvent.scheduled()) 205 return 0; 206 drainEvent = de; 207 return 1; 208} 209