packet_queue.cc revision 13565:fe1169a7502d
1/* 2 * Copyright (c) 2012,2015,2018 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 "mem/packet_queue.hh" 45 46#include "base/trace.hh" 47#include "debug/Drain.hh" 48#include "debug/PacketQueue.hh" 49 50PacketQueue::PacketQueue(EventManager& _em, const std::string& _label, 51 const std::string& _sendEventName, 52 bool force_order, 53 bool disable_sanity_check) 54 : em(_em), sendEvent([this]{ processSendEvent(); }, _sendEventName), 55 _disableSanityCheck(disable_sanity_check), 56 forceOrder(force_order), 57 label(_label), waitingOnRetry(false) 58{ 59} 60 61PacketQueue::~PacketQueue() 62{ 63} 64 65void 66PacketQueue::retry() 67{ 68 DPRINTF(PacketQueue, "Queue %s received retry\n", name()); 69 assert(waitingOnRetry); 70 waitingOnRetry = false; 71 sendDeferredPacket(); 72} 73 74bool 75PacketQueue::hasAddr(Addr addr) const 76{ 77 // caller is responsible for ensuring that all packets have the 78 // same alignment 79 for (const auto& p : transmitList) { 80 if (p.pkt->getAddr() == addr) 81 return true; 82 } 83 return false; 84} 85 86bool 87PacketQueue::trySatisfyFunctional(PacketPtr pkt) 88{ 89 pkt->pushLabel(label); 90 91 auto i = transmitList.begin(); 92 bool found = false; 93 94 while (!found && i != transmitList.end()) { 95 // If the buffered packet contains data, and it overlaps the 96 // current packet, then update data 97 found = pkt->trySatisfyFunctional(i->pkt); 98 ++i; 99 } 100 101 pkt->popLabel(); 102 103 return found; 104} 105 106void 107PacketQueue::schedSendTiming(PacketPtr pkt, Tick when) 108{ 109 DPRINTF(PacketQueue, "%s for %s address %x size %d when %lu ord: %i\n", 110 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize(), when, 111 forceOrder); 112 113 // we can still send a packet before the end of this tick 114 assert(when >= curTick()); 115 116 // express snoops should never be queued 117 assert(!pkt->isExpressSnoop()); 118 119 // add a very basic sanity check on the port to ensure the 120 // invisible buffer is not growing beyond reasonable limits 121 if (!_disableSanityCheck && transmitList.size() > 100) { 122 panic("Packet queue %s has grown beyond 100 packets\n", 123 name()); 124 } 125 126 // we should either have an outstanding retry, or a send event 127 // scheduled, but there is an unfortunate corner case where the 128 // x86 page-table walker and timing CPU send out a new request as 129 // part of the receiving of a response (called by 130 // PacketQueue::sendDeferredPacket), in which we end up calling 131 // ourselves again before we had a chance to update waitingOnRetry 132 // assert(waitingOnRetry || sendEvent.scheduled()); 133 134 // this belongs in the middle somewhere, so search from the end to 135 // order by tick; however, if forceOrder is set, also make sure 136 // not to re-order in front of some existing packet with the same 137 // address 138 auto it = transmitList.end(); 139 while (it != transmitList.begin()) { 140 --it; 141 if ((forceOrder && it->pkt->getAddr() == pkt->getAddr()) || 142 it->tick <= when) { 143 // emplace inserts the element before the position pointed to by 144 // the iterator, so advance it one step 145 transmitList.emplace(++it, when, pkt); 146 return; 147 } 148 } 149 // either the packet list is empty or this has to be inserted 150 // before every other packet 151 transmitList.emplace_front(when, pkt); 152 schedSendEvent(when); 153} 154 155void 156PacketQueue::schedSendEvent(Tick when) 157{ 158 // if we are waiting on a retry just hold off 159 if (waitingOnRetry) { 160 DPRINTF(PacketQueue, "Not scheduling send as waiting for retry\n"); 161 assert(!sendEvent.scheduled()); 162 return; 163 } 164 165 if (when != MaxTick) { 166 // we cannot go back in time, and to be consistent we stick to 167 // one tick in the future 168 when = std::max(when, curTick() + 1); 169 // @todo Revisit the +1 170 171 if (!sendEvent.scheduled()) { 172 em.schedule(&sendEvent, when); 173 } else if (when < sendEvent.when()) { 174 // if the new time is earlier than when the event 175 // currently is scheduled, move it forward 176 em.reschedule(&sendEvent, when); 177 } 178 } else { 179 // we get a MaxTick when there is no more to send, so if we're 180 // draining, we may be done at this point 181 if (drainState() == DrainState::Draining && 182 transmitList.empty() && !sendEvent.scheduled()) { 183 184 DPRINTF(Drain, "PacketQueue done draining," 185 "processing drain event\n"); 186 signalDrainDone(); 187 } 188 } 189} 190 191void 192PacketQueue::sendDeferredPacket() 193{ 194 // sanity checks 195 assert(!waitingOnRetry); 196 assert(deferredPacketReady()); 197 198 DeferredPacket dp = transmitList.front(); 199 200 // take the packet of the list before sending it, as sending of 201 // the packet in some cases causes a new packet to be enqueued 202 // (most notaly when responding to the timing CPU, leading to a 203 // new request hitting in the L1 icache, leading to a new 204 // response) 205 transmitList.pop_front(); 206 207 // use the appropriate implementation of sendTiming based on the 208 // type of queue 209 waitingOnRetry = !sendTiming(dp.pkt); 210 211 // if we succeeded and are not waiting for a retry, schedule the 212 // next send 213 if (!waitingOnRetry) { 214 schedSendEvent(deferredPacketReadyTime()); 215 } else { 216 // put the packet back at the front of the list 217 transmitList.emplace_front(dp); 218 } 219} 220 221void 222PacketQueue::processSendEvent() 223{ 224 assert(!waitingOnRetry); 225 sendDeferredPacket(); 226} 227 228DrainState 229PacketQueue::drain() 230{ 231 if (transmitList.empty()) { 232 return DrainState::Drained; 233 } else { 234 DPRINTF(Drain, "PacketQueue not drained\n"); 235 return DrainState::Draining; 236 } 237} 238 239ReqPacketQueue::ReqPacketQueue(EventManager& _em, MasterPort& _masterPort, 240 const std::string _label) 241 : PacketQueue(_em, _label, name(_masterPort, _label)), 242 masterPort(_masterPort) 243{ 244} 245 246bool 247ReqPacketQueue::sendTiming(PacketPtr pkt) 248{ 249 return masterPort.sendTimingReq(pkt); 250} 251 252SnoopRespPacketQueue::SnoopRespPacketQueue(EventManager& _em, 253 MasterPort& _masterPort, 254 bool force_order, 255 const std::string _label) 256 : PacketQueue(_em, _label, name(_masterPort, _label), force_order), 257 masterPort(_masterPort) 258{ 259} 260 261bool 262SnoopRespPacketQueue::sendTiming(PacketPtr pkt) 263{ 264 return masterPort.sendTimingSnoopResp(pkt); 265} 266 267RespPacketQueue::RespPacketQueue(EventManager& _em, SlavePort& _slavePort, 268 bool force_order, 269 const std::string _label) 270 : PacketQueue(_em, _label, name(_slavePort, _label), force_order), 271 slavePort(_slavePort) 272{ 273} 274 275bool 276RespPacketQueue::sendTiming(PacketPtr pkt) 277{ 278 return slavePort.sendTimingResp(pkt); 279} 280