packet_queue.hh revision 8914
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 61/** 62 * A packet queue is a class that holds deferred packets and later 63 * sends them using the associated slave port or master port. 64 */ 65class PacketQueue 66{ 67 private: 68 /** A deferred packet, buffered to transmit later. */ 69 class DeferredPacket { 70 public: 71 Tick tick; ///< The tick when the packet is ready to transmit 72 PacketPtr pkt; ///< Pointer to the packet to transmit 73 DeferredPacket(Tick t, PacketPtr p) 74 : tick(t), pkt(p) 75 {} 76 }; 77 78 typedef std::list<DeferredPacket> DeferredPacketList; 79 typedef std::list<DeferredPacket>::iterator DeferredPacketIterator; 80 81 /** A list of outgoing timing response packets that haven't been 82 * serviced yet. */ 83 DeferredPacketList transmitList; 84 85 /** The manager which is used for the event queue */ 86 EventManager& em; 87 88 /** Label to use for print request packets label stack. */ 89 const std::string label; 90 91 /** This function attempts to send deferred packets. Scheduled to 92 * be called in the future via SendEvent. */ 93 void processSendEvent(); 94 95 /** 96 * Event used to call processSendEvent. 97 **/ 98 EventWrapper<PacketQueue, &PacketQueue::processSendEvent> sendEvent; 99 100 /** If we need to drain, keep the drain event around until we're done 101 * here.*/ 102 Event *drainEvent; 103 104 protected: 105 106 /** The port used to send the packets. */ 107 Port& port; 108 109 /** Remember whether we're awaiting a retry from the bus. */ 110 bool waitingOnRetry; 111 112 /** Check whether we have a packet ready to go on the transmit list. */ 113 bool deferredPacketReady() 114 { return !transmitList.empty() && transmitList.front().tick <= curTick(); } 115 116 Tick deferredPacketReadyTime() 117 { return transmitList.empty() ? MaxTick : transmitList.front().tick; } 118 119 /** 120 * Attempt to send the packet at the head of the transmit 121 * list. Caller must guarantee that the list is non-empty and that 122 * the head packet is scheduled for curTick() (or earlier). Note 123 * that a subclass of the PacketQueue can override this method and 124 * thus change the behaviour (as done by the cache). 125 */ 126 virtual void sendDeferredPacket(); 127 128 /** 129 * Attempt to send the packet at the front of the transmit list, 130 * and set waitingOnRetry accordingly. The packet is temporarily 131 * taken off the list, but put back at the front if not 132 * successfully sent. 133 */ 134 void trySendTiming(); 135 136 /** 137 * Based on the transmit list, or the provided time, schedule a 138 * send event if there are packets to send. If we are idle and 139 * asked to drain then do so. 140 * 141 * @param time an alternative time for the next send event 142 */ 143 void scheduleSend(Tick time = MaxTick); 144 145 /** 146 * Simple ports are generally used as slave ports (i.e. the 147 * respond to requests) and thus do not expect to receive any 148 * range changes (as the neighbouring port has a master role and 149 * do not have any address ranges. A subclass can override the 150 * default behaviuor if needed. 151 */ 152 virtual void recvRangeChange() { } 153 154 public: 155 156 /** 157 * Create a packet queue, linked to an event manager, a port used 158 * to send the packets, and potentially give it a label that will 159 * be used for functional print request packets. 160 * 161 * @param _em Event manager used for scheduling this queue 162 * @param _port Port used to send the packets 163 * @param _label Label to push on the label stack for print request packets 164 */ 165 PacketQueue(EventManager& _em, Port& _port, 166 const std::string _label = "PacketQueue"); 167 168 /** 169 * Virtual desctructor since the class may be used as a base class. 170 */ 171 virtual ~PacketQueue(); 172 173 /** 174 * Provide a name to simplify debugging. Base it on the port. 175 * 176 * @return A complete name, appended to module and port 177 */ 178 const std::string name() const { return port.name() + "-queue"; } 179 180 /** Check the list of buffered packets against the supplied 181 * functional request. */ 182 bool checkFunctional(PacketPtr pkt); 183 184 /** 185 * Schedule a send even if not already waiting for a retry. If the 186 * requested time is before an already scheduled send event it 187 * will be rescheduled. 188 * 189 * @param when 190 */ 191 void schedSendEvent(Tick when); 192 193 /** 194 * Add a packet to the transmit list, and ensure that a 195 * processSendEvent is called in the future. 196 * 197 * @param pkt Packet to send 198 * @param when Absolute time (in ticks) to send packet 199 */ 200 void schedSendTiming(PacketPtr pkt, Tick when); 201 202 /** 203 * Used by a port to notify the queue that a retry was received 204 * and that the queue can proceed and retry sending the packet 205 * that caused the wait. 206 */ 207 void retry(); 208 209 /** 210 * Hook for draining the packet queue. 211 * 212 * @param de An event which is used to signal back to the caller 213 * @return A number indicating how many times process will be called 214 */ 215 unsigned int drain(Event *de); 216}; 217 218#endif // __MEM_TPORT_HH__ 219