packet_queue.hh revision 9342
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#ifndef __MEM_PACKET_QUEUE_HH__ 45#define __MEM_PACKET_QUEUE_HH__ 46 47/** 48 * @file 49 * Declaration of a simple PacketQueue that is associated with 50 * a port on which it attempts to send packets according to the time 51 * stamp given to them at insertion. The packet queue is responsible 52 * for the flow control of the port, but relies on the module 53 * notifying the queue when a transfer ends. 54 */ 55 56#include <list> 57 58#include "mem/port.hh" 59#include "sim/eventq.hh" 60#include "sim/drain.hh" 61 62/** 63 * A packet queue is a class that holds deferred packets and later 64 * sends them using the associated slave port or master port. 65 */ 66class PacketQueue : public Drainable 67{ 68 private: 69 /** A deferred packet, buffered to transmit later. */ 70 class DeferredPacket { 71 public: 72 Tick tick; ///< The tick when the packet is ready to transmit 73 PacketPtr pkt; ///< Pointer to the packet to transmit 74 bool sendAsSnoop; ///< Should it be sent as a snoop or not 75 DeferredPacket(Tick t, PacketPtr p, bool send_as_snoop) 76 : tick(t), pkt(p), sendAsSnoop(send_as_snoop) 77 {} 78 }; 79 80 typedef std::list<DeferredPacket> DeferredPacketList; 81 typedef std::list<DeferredPacket>::iterator DeferredPacketIterator; 82 83 /** A list of outgoing timing response packets that haven't been 84 * serviced yet. */ 85 DeferredPacketList transmitList; 86 87 /** The manager which is used for the event queue */ 88 EventManager& em; 89 90 /** This function attempts to send deferred packets. Scheduled to 91 * be called in the future via SendEvent. */ 92 void processSendEvent(); 93 94 /** 95 * Event used to call processSendEvent. 96 **/ 97 EventWrapper<PacketQueue, &PacketQueue::processSendEvent> sendEvent; 98 99 /** If we need to drain, keep the drain manager around until we're done 100 * here.*/ 101 DrainManager *drainManager; 102 103 protected: 104 105 /** Label to use for print request packets label stack. */ 106 const std::string label; 107 108 /** Remember whether we're awaiting a retry from the bus. */ 109 bool waitingOnRetry; 110 111 /** Check whether we have a packet ready to go on the transmit list. */ 112 bool deferredPacketReady() 113 { return !transmitList.empty() && transmitList.front().tick <= curTick(); } 114 115 Tick deferredPacketReadyTime() 116 { return transmitList.empty() ? MaxTick : transmitList.front().tick; } 117 118 /** 119 * Attempt to send the packet at the head of the transmit 120 * list. Caller must guarantee that the list is non-empty and that 121 * the head packet is scheduled for curTick() (or earlier). Note 122 * that a subclass of the PacketQueue can override this method and 123 * thus change the behaviour (as done by the cache). 124 */ 125 virtual void sendDeferredPacket(); 126 127 /** 128 * Attempt to send the packet at the front of the transmit list, 129 * and set waitingOnRetry accordingly. The packet is temporarily 130 * taken off the list, but put back at the front if not 131 * successfully sent. 132 */ 133 void trySendTiming(); 134 135 /** 136 * 137 */ 138 virtual bool sendTiming(PacketPtr pkt, bool send_as_snoop) = 0; 139 140 /** 141 * Based on the transmit list, or the provided time, schedule a 142 * send event if there are packets to send. If we are idle and 143 * asked to drain then do so. 144 * 145 * @param time an alternative time for the next send event 146 */ 147 void scheduleSend(Tick time = MaxTick); 148 149 /** 150 * Simple ports are generally used as slave ports (i.e. the 151 * respond to requests) and thus do not expect to receive any 152 * range changes (as the neighbouring port has a master role and 153 * do not have any address ranges. A subclass can override the 154 * default behaviuor if needed. 155 */ 156 virtual void recvRangeChange() { } 157 158 /** 159 * Create a packet queue, linked to an event manager, and a label 160 * that will be used for functional print request packets. 161 * 162 * @param _em Event manager used for scheduling this queue 163 * @param _label Label to push on the label stack for print request packets 164 */ 165 PacketQueue(EventManager& _em, const std::string& _label); 166 167 /** 168 * Virtual desctructor since the class may be used as a base class. 169 */ 170 virtual ~PacketQueue(); 171 172 public: 173 174 /** 175 * Provide a name to simplify debugging. 176 * 177 * @return A complete name, appended to module and port 178 */ 179 virtual const std::string name() const = 0; 180 181 /** Check the list of buffered packets against the supplied 182 * functional request. */ 183 bool checkFunctional(PacketPtr pkt); 184 185 /** 186 * Schedule a send even if not already waiting for a retry. If the 187 * requested time is before an already scheduled send event it 188 * will be rescheduled. 189 * 190 * @param when 191 */ 192 void schedSendEvent(Tick when); 193 194 /** 195 * Add a packet to the transmit list, and ensure that a 196 * processSendEvent is called in the future. 197 * 198 * @param pkt Packet to send 199 * @param when Absolute time (in ticks) to send packet 200 * @param send_as_snoop Send the packet as a snoop or not 201 */ 202 void schedSendTiming(PacketPtr pkt, Tick when, bool send_as_snoop = false); 203 204 /** 205 * Used by a port to notify the queue that a retry was received 206 * and that the queue can proceed and retry sending the packet 207 * that caused the wait. 208 */ 209 void retry(); 210 211 unsigned int drain(DrainManager *dm); 212}; 213 214class MasterPacketQueue : public PacketQueue 215{ 216 217 protected: 218 219 MasterPort& masterPort; 220 221 public: 222 223 /** 224 * Create a master packet queue, linked to an event manager, a 225 * master port, and a label that will be used for functional print 226 * request packets. 227 * 228 * @param _em Event manager used for scheduling this queue 229 * @param _masterPort Master port used to send the packets 230 * @param _label Label to push on the label stack for print request packets 231 */ 232 MasterPacketQueue(EventManager& _em, MasterPort& _masterPort, 233 const std::string _label = "MasterPacketQueue"); 234 235 virtual ~MasterPacketQueue() { } 236 237 const std::string name() const 238 { return masterPort.name() + "-" + label; } 239 240 bool sendTiming(PacketPtr pkt, bool send_as_snoop); 241}; 242 243class SlavePacketQueue : public PacketQueue 244{ 245 246 protected: 247 248 SlavePort& slavePort; 249 250 public: 251 252 /** 253 * Create a slave packet queue, linked to an event manager, a 254 * slave port, and a label that will be used for functional print 255 * request packets. 256 * 257 * @param _em Event manager used for scheduling this queue 258 * @param _slavePort Slave port used to send the packets 259 * @param _label Label to push on the label stack for print request packets 260 */ 261 SlavePacketQueue(EventManager& _em, SlavePort& _slavePort, 262 const std::string _label = "SlavePacketQueue"); 263 264 virtual ~SlavePacketQueue() { } 265 266 const std::string name() const 267 { return slavePort.name() + "-" + label; } 268 269 bool sendTiming(PacketPtr pkt, bool send_as_snoop); 270 271}; 272 273#endif // __MEM_PACKET_QUEUE_HH__ 274