packet_queue.cc revision 11195
1/* 2 * Copyright (c) 2012,2015 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 "base/trace.hh" 45#include "debug/Drain.hh" 46#include "debug/PacketQueue.hh" 47#include "mem/packet_queue.hh" 48 49using namespace std; 50 51PacketQueue::PacketQueue(EventManager& _em, const std::string& _label) 52 : em(_em), sendEvent(this), label(_label), 53 waitingOnRetry(false) 54{ 55} 56 57PacketQueue::~PacketQueue() 58{ 59} 60 61void 62PacketQueue::retry() 63{ 64 DPRINTF(PacketQueue, "Queue %s received retry\n", name()); 65 assert(waitingOnRetry); 66 waitingOnRetry = false; 67 sendDeferredPacket(); 68} 69 70bool 71PacketQueue::hasAddr(Addr addr) const 72{ 73 // caller is responsible for ensuring that all packets have the 74 // same alignment 75 for (const auto& p : transmitList) { 76 if (p.pkt->getAddr() == addr) 77 return true; 78 } 79 return false; 80} 81 82bool 83PacketQueue::checkFunctional(PacketPtr pkt) 84{ 85 pkt->pushLabel(label); 86 87 auto i = transmitList.begin(); 88 bool found = false; 89 90 while (!found && i != transmitList.end()) { 91 // If the buffered packet contains data, and it overlaps the 92 // current packet, then update data 93 found = pkt->checkFunctional(i->pkt); 94 ++i; 95 } 96 97 pkt->popLabel(); 98 99 return found; 100} 101 102void 103PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool force_order) 104{ 105 DPRINTF(PacketQueue, "%s for %s address %x size %d when %lu ord: %i\n", 106 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize(), when, 107 force_order); 108 109 // we can still send a packet before the end of this tick 110 assert(when >= curTick()); 111 112 // express snoops should never be queued 113 assert(!pkt->isExpressSnoop()); 114 115 // add a very basic sanity check on the port to ensure the 116 // invisible buffer is not growing beyond reasonable limits 117 if (transmitList.size() > 100) { 118 panic("Packet queue %s has grown beyond 100 packets\n", 119 name()); 120 } 121 122 // nothing on the list 123 if (transmitList.empty()) { 124 transmitList.emplace_front(when, pkt); 125 schedSendEvent(when); 126 return; 127 } 128 129 // we should either have an outstanding retry, or a send event 130 // scheduled, but there is an unfortunate corner case where the 131 // x86 page-table walker and timing CPU send out a new request as 132 // part of the receiving of a response (called by 133 // PacketQueue::sendDeferredPacket), in which we end up calling 134 // ourselves again before we had a chance to update waitingOnRetry 135 // assert(waitingOnRetry || sendEvent.scheduled()); 136 137 // this belongs in the middle somewhere, so search from the end to 138 // order by tick; however, if force_order is set, also make sure 139 // not to re-order in front of some existing packet with the same 140 // address 141 auto i = transmitList.end(); 142 --i; 143 while (i != transmitList.begin() && when < i->tick && 144 !(force_order && i->pkt->getAddr() == pkt->getAddr())) 145 --i; 146 147 // emplace inserts the element before the position pointed to by 148 // the iterator, so advance it one step 149 transmitList.emplace(++i, when, pkt); 150} 151 152void 153PacketQueue::schedSendEvent(Tick when) 154{ 155 // if we are waiting on a retry just hold off 156 if (waitingOnRetry) { 157 DPRINTF(PacketQueue, "Not scheduling send as waiting for retry\n"); 158 assert(!sendEvent.scheduled()); 159 return; 160 } 161 162 if (when != MaxTick) { 163 // we cannot go back in time, and to be consistent we stick to 164 // one tick in the future 165 when = std::max(when, curTick() + 1); 166 // @todo Revisit the +1 167 168 if (!sendEvent.scheduled()) { 169 em.schedule(&sendEvent, when); 170 } else if (when < sendEvent.when()) { 171 // if the new time is earlier than when the event 172 // currently is scheduled, move it forward 173 em.reschedule(&sendEvent, when); 174 } 175 } else { 176 // we get a MaxTick when there is no more to send, so if we're 177 // draining, we may be done at this point 178 if (drainState() == DrainState::Draining && 179 transmitList.empty() && !sendEvent.scheduled()) { 180 181 DPRINTF(Drain, "PacketQueue done draining," 182 "processing drain event\n"); 183 signalDrainDone(); 184 } 185 } 186} 187 188void 189PacketQueue::sendDeferredPacket() 190{ 191 // sanity checks 192 assert(!waitingOnRetry); 193 assert(deferredPacketReady()); 194 195 DeferredPacket dp = transmitList.front(); 196 197 // take the packet of the list before sending it, as sending of 198 // the packet in some cases causes a new packet to be enqueued 199 // (most notaly when responding to the timing CPU, leading to a 200 // new request hitting in the L1 icache, leading to a new 201 // response) 202 transmitList.pop_front(); 203 204 // use the appropriate implementation of sendTiming based on the 205 // type of queue 206 waitingOnRetry = !sendTiming(dp.pkt); 207 208 // if we succeeded and are not waiting for a retry, schedule the 209 // next send 210 if (!waitingOnRetry) { 211 schedSendEvent(deferredPacketReadyTime()); 212 } else { 213 // put the packet back at the front of the list 214 transmitList.emplace_front(dp); 215 } 216} 217 218void 219PacketQueue::processSendEvent() 220{ 221 assert(!waitingOnRetry); 222 sendDeferredPacket(); 223} 224 225DrainState 226PacketQueue::drain() 227{ 228 if (transmitList.empty()) { 229 return DrainState::Drained; 230 } else { 231 DPRINTF(Drain, "PacketQueue not drained\n"); 232 return DrainState::Draining; 233 } 234} 235 236ReqPacketQueue::ReqPacketQueue(EventManager& _em, MasterPort& _masterPort, 237 const std::string _label) 238 : PacketQueue(_em, _label), masterPort(_masterPort) 239{ 240} 241 242bool 243ReqPacketQueue::sendTiming(PacketPtr pkt) 244{ 245 return masterPort.sendTimingReq(pkt); 246} 247 248SnoopRespPacketQueue::SnoopRespPacketQueue(EventManager& _em, 249 MasterPort& _masterPort, 250 const std::string _label) 251 : PacketQueue(_em, _label), masterPort(_masterPort) 252{ 253} 254 255bool 256SnoopRespPacketQueue::sendTiming(PacketPtr pkt) 257{ 258 return masterPort.sendTimingSnoopResp(pkt); 259} 260 261RespPacketQueue::RespPacketQueue(EventManager& _em, SlavePort& _slavePort, 262 const std::string _label) 263 : PacketQueue(_em, _label), slavePort(_slavePort) 264{ 265} 266 267bool 268RespPacketQueue::sendTiming(PacketPtr pkt) 269{ 270 return slavePort.sendTimingResp(pkt); 271} 272