packet_queue.hh revision 10722:886d2458e0d6 
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#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.
53 */
54
55#include <list>
56
57#include "mem/port.hh"
58#include "sim/drain.hh"
59#include "sim/eventq_impl.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 : public Drainable
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
80    /** A list of outgoing packets. */
81    DeferredPacketList transmitList;
82
83    /** The manager which is used for the event queue */
84    EventManager& em;
85
86    /** Used to schedule sending of deferred packets. */
87    void processSendEvent();
88
89    /** Event used to call processSendEvent. */
90    EventWrapper<PacketQueue, &PacketQueue::processSendEvent> sendEvent;
91
92    /** If we need to drain, keep the drain manager around until we're done
93     * here.*/
94    DrainManager *drainManager;
95
96  protected:
97
98    /** Label to use for print request packets label stack. */
99    const std::string label;
100
101    /** Remember whether we're awaiting a retry. */
102    bool waitingOnRetry;
103
104    /** Check whether we have a packet ready to go on the transmit list. */
105    bool deferredPacketReady() const
106    { return !transmitList.empty() && transmitList.front().tick <= curTick(); }
107
108    /**
109     * Attempt to send a packet. Note that a subclass of the
110     * PacketQueue can override this method and thus change the
111     * behaviour (as done by the cache for the request queue). The
112     * default implementation sends the head of the transmit list. The
113     * caller must guarantee that the list is non-empty and that the
114     * head packet is scheduled for curTick() (or earlier).
115     */
116    virtual void sendDeferredPacket();
117
118    /**
119     * Send a packet using the appropriate method for the specific
120     * subclass (reuest, response or snoop response).
121     */
122    virtual bool sendTiming(PacketPtr pkt) = 0;
123
124    /**
125     * Create a packet queue, linked to an event manager, and a label
126     * that will be used for functional print request packets.
127     *
128     * @param _em Event manager used for scheduling this queue
129     * @param _label Label to push on the label stack for print request packets
130     */
131    PacketQueue(EventManager& _em, const std::string& _label);
132
133    /**
134     * Virtual desctructor since the class may be used as a base class.
135     */
136    virtual ~PacketQueue();
137
138  public:
139
140    /**
141     * Provide a name to simplify debugging.
142     *
143     * @return A complete name, appended to module and port
144     */
145    virtual const std::string name() const = 0;
146
147    /**
148     * Get the size of the queue.
149     */
150    size_t size() const { return transmitList.size(); }
151
152    /**
153     * Get the next packet ready time.
154     */
155    Tick deferredPacketReadyTime() const
156    { return transmitList.empty() ? MaxTick : transmitList.front().tick; }
157
158    /**
159     * Check if a packets address exists in the queue.
160     */
161    bool hasAddr(Addr addr) const;
162
163    /** Check the list of buffered packets against the supplied
164     * functional request. */
165    bool checkFunctional(PacketPtr pkt);
166
167    /**
168     * Schedule a send event if we are not already waiting for a
169     * retry. If the requested time is before an already scheduled
170     * send event, the event will be rescheduled. If MaxTick is
171     * passed, no event is scheduled. Instead, if we are idle and
172     * asked to drain then check and signal drained.
173     *
174     * @param when time to schedule an event
175     */
176    void schedSendEvent(Tick when);
177
178    /**
179     * Add a packet to the transmit list, and schedule a send event.
180     *
181     * @param pkt Packet to send
182     * @param when Absolute time (in ticks) to send packet
183     * @param force_order Do not reorder packets despite timing, but keep them
184     *                    in insertion order.
185     */
186    void schedSendTiming(PacketPtr pkt, Tick when, bool force_order = false);
187
188    /**
189     * Retry sending a packet from the queue. Note that this is not
190     * necessarily the same packet if something has been added with an
191     * earlier time stamp.
192     */
193    void retry();
194
195    unsigned int drain(DrainManager *dm);
196};
197
198class ReqPacketQueue : public PacketQueue
199{
200
201  protected:
202
203    MasterPort& masterPort;
204
205  public:
206
207    /**
208     * Create a request packet queue, linked to an event manager, a
209     * master port, and a label that will be used for functional print
210     * request packets.
211     *
212     * @param _em Event manager used for scheduling this queue
213     * @param _masterPort Master port used to send the packets
214     * @param _label Label to push on the label stack for print request packets
215     */
216    ReqPacketQueue(EventManager& _em, MasterPort& _masterPort,
217                   const std::string _label = "ReqPacketQueue");
218
219    virtual ~ReqPacketQueue() { }
220
221    const std::string name() const
222    { return masterPort.name() + "-" + label; }
223
224    bool sendTiming(PacketPtr pkt);
225
226};
227
228class SnoopRespPacketQueue : public PacketQueue
229{
230
231  protected:
232
233    MasterPort& masterPort;
234
235  public:
236
237    /**
238     * Create a snoop response packet queue, linked to an event
239     * manager, a master port, and a label that will be used for
240     * functional print request packets.
241     *
242     * @param _em Event manager used for scheduling this queue
243     * @param _masterPort Master port used to send the packets
244     * @param _label Label to push on the label stack for print request packets
245     */
246    SnoopRespPacketQueue(EventManager& _em, MasterPort& _masterPort,
247                         const std::string _label = "SnoopRespPacketQueue");
248
249    virtual ~SnoopRespPacketQueue() { }
250
251    const std::string name() const
252    { return masterPort.name() + "-" + label; }
253
254    bool sendTiming(PacketPtr pkt);
255
256};
257
258class RespPacketQueue : public PacketQueue
259{
260
261  protected:
262
263    SlavePort& slavePort;
264
265  public:
266
267    /**
268     * Create a response packet queue, linked to an event manager, a
269     * slave port, and a label that will be used for functional print
270     * request packets.
271     *
272     * @param _em Event manager used for scheduling this queue
273     * @param _slavePort Slave port used to send the packets
274     * @param _label Label to push on the label stack for print request packets
275     */
276    RespPacketQueue(EventManager& _em, SlavePort& _slavePort,
277                     const std::string _label = "RespPacketQueue");
278
279    virtual ~RespPacketQueue() { }
280
281    const std::string name() const
282    { return slavePort.name() + "-" + label; }
283
284    bool sendTiming(PacketPtr pkt);
285
286};
287
288#endif // __MEM_PACKET_QUEUE_HH__
289