packet_queue.hh 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#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 bool sendAsSnoop; ///< Should it be sent as a snoop or not 74 DeferredPacket(Tick t, PacketPtr p, bool send_as_snoop) 75 : tick(t), pkt(p), sendAsSnoop(send_as_snoop) 76 {} 77 }; 78 79 typedef std::list<DeferredPacket> DeferredPacketList; 80 typedef std::list<DeferredPacket>::iterator DeferredPacketIterator; 81 82 /** A list of outgoing timing response packets that haven't been 83 * serviced yet. */ 84 DeferredPacketList transmitList; 85 86 /** The manager which is used for the event queue */ 87 EventManager& em; 88 89 /** Label to use for print request packets label stack. */ 90 const std::string label; 91 92 /** This function attempts to send deferred packets. Scheduled to 93 * be called in the future via SendEvent. */ 94 void processSendEvent(); 95 96 /** 97 * Event used to call processSendEvent. 98 **/ 99 EventWrapper<PacketQueue, &PacketQueue::processSendEvent> sendEvent; 100 101 /** If we need to drain, keep the drain event around until we're done 102 * here.*/ 103 Event *drainEvent; 104 105 protected: 106 107 /** The port used to send the packets. */ 108 Port& port; 109 110 /** Remember whether we're awaiting a retry from the bus. */ 111 bool waitingOnRetry; 112 113 /** Check whether we have a packet ready to go on the transmit list. */ 114 bool deferredPacketReady() 115 { return !transmitList.empty() && transmitList.front().tick <= curTick(); } 116 117 Tick deferredPacketReadyTime() 118 { return transmitList.empty() ? MaxTick : transmitList.front().tick; } 119 120 /** 121 * Attempt to send the packet at the head of the transmit 122 * list. Caller must guarantee that the list is non-empty and that 123 * the head packet is scheduled for curTick() (or earlier). Note 124 * that a subclass of the PacketQueue can override this method and 125 * thus change the behaviour (as done by the cache). 126 */ 127 virtual void sendDeferredPacket(); 128 129 /** 130 * Attempt to send the packet at the front of the transmit list, 131 * and set waitingOnRetry accordingly. The packet is temporarily 132 * taken off the list, but put back at the front if not 133 * successfully sent. 134 */ 135 void trySendTiming(); 136 137 /** 138 * Based on the transmit list, or the provided time, schedule a 139 * send event if there are packets to send. If we are idle and 140 * asked to drain then do so. 141 * 142 * @param time an alternative time for the next send event 143 */ 144 void scheduleSend(Tick time = MaxTick); 145 146 /** 147 * Simple ports are generally used as slave ports (i.e. the 148 * respond to requests) and thus do not expect to receive any 149 * range changes (as the neighbouring port has a master role and 150 * do not have any address ranges. A subclass can override the 151 * default behaviuor if needed. 152 */ 153 virtual void recvRangeChange() { } 154 155 public: 156 157 /** 158 * Create a packet queue, linked to an event manager, a port used 159 * to send the packets, and potentially give it a label that will 160 * be used for functional print request packets. 161 * 162 * @param _em Event manager used for scheduling this queue 163 * @param _port Port used to send the packets 164 * @param _label Label to push on the label stack for print request packets 165 */ 166 PacketQueue(EventManager& _em, Port& _port, 167 const std::string _label = "PacketQueue"); 168 169 /** 170 * Virtual desctructor since the class may be used as a base class. 171 */ 172 virtual ~PacketQueue(); 173 174 /** 175 * Provide a name to simplify debugging. Base it on the port. 176 * 177 * @return A complete name, appended to module and port 178 */ 179 const std::string name() const { return port.name() + "-queue"; } 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 /** 212 * Hook for draining the packet queue. 213 * 214 * @param de An event which is used to signal back to the caller 215 * @return A number indicating how many times process will be called 216 */ 217 unsigned int drain(Event *de); 218}; 219 220#endif // __MEM_PACKET_QUEUE_HH__ 221