packet_queue.hh revision 11195 
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  protected:
93
94    /** Label to use for print request packets label stack. */
95    const std::string label;
96
97    /** Remember whether we're awaiting a retry. */
98    bool waitingOnRetry;
99
100    /** Check whether we have a packet ready to go on the transmit list. */
101    bool deferredPacketReady() const
102    { return !transmitList.empty() && transmitList.front().tick <= curTick(); }
103
104    /**
105     * Attempt to send a packet. Note that a subclass of the
106     * PacketQueue can override this method and thus change the
107     * behaviour (as done by the cache for the request queue). The
108     * default implementation sends the head of the transmit list. The
109     * caller must guarantee that the list is non-empty and that the
110     * head packet is scheduled for curTick() (or earlier).
111     */
112    virtual void sendDeferredPacket();
113
114    /**
115     * Send a packet using the appropriate method for the specific
116     * subclass (reuest, response or snoop response).
117     */
118    virtual bool sendTiming(PacketPtr pkt) = 0;
119
120    /**
121     * Create a packet queue, linked to an event manager, and a label
122     * that will be used for functional print request packets.
123     *
124     * @param _em Event manager used for scheduling this queue
125     * @param _label Label to push on the label stack for print request packets
126     */
127    PacketQueue(EventManager& _em, const std::string& _label);
128
129    /**
130     * Virtual desctructor since the class may be used as a base class.
131     */
132    virtual ~PacketQueue();
133
134  public:
135
136    /**
137     * Provide a name to simplify debugging.
138     *
139     * @return A complete name, appended to module and port
140     */
141    virtual const std::string name() const = 0;
142
143    /**
144     * Get the size of the queue.
145     */
146    size_t size() const { return transmitList.size(); }
147
148    /**
149     * Get the next packet ready time.
150     */
151    Tick deferredPacketReadyTime() const
152    { return transmitList.empty() ? MaxTick : transmitList.front().tick; }
153
154    /**
155     * Check if a packets address exists in the queue.
156     */
157    bool hasAddr(Addr addr) const;
158
159    /** Check the list of buffered packets against the supplied
160     * functional request. */
161    bool checkFunctional(PacketPtr pkt);
162
163    /**
164     * Schedule a send event if we are not already waiting for a
165     * retry. If the requested time is before an already scheduled
166     * send event, the event will be rescheduled. If MaxTick is
167     * passed, no event is scheduled. Instead, if we are idle and
168     * asked to drain then check and signal drained.
169     *
170     * @param when time to schedule an event
171     */
172    void schedSendEvent(Tick when);
173
174    /**
175     * Add a packet to the transmit list, and schedule a send event.
176     *
177     * @param pkt Packet to send
178     * @param when Absolute time (in ticks) to send packet
179     * @param force_order Force insertion order for packets with same address
180     */
181    void schedSendTiming(PacketPtr pkt, Tick when, bool force_order = false);
182
183    /**
184     * Retry sending a packet from the queue. Note that this is not
185     * necessarily the same packet if something has been added with an
186     * earlier time stamp.
187     */
188    void retry();
189
190    DrainState drain() override;
191};
192
193class ReqPacketQueue : public PacketQueue
194{
195
196  protected:
197
198    MasterPort& masterPort;
199
200  public:
201
202    /**
203     * Create a request packet queue, linked to an event manager, a
204     * master port, and a label that will be used for functional print
205     * request packets.
206     *
207     * @param _em Event manager used for scheduling this queue
208     * @param _masterPort Master port used to send the packets
209     * @param _label Label to push on the label stack for print request packets
210     */
211    ReqPacketQueue(EventManager& _em, MasterPort& _masterPort,
212                   const std::string _label = "ReqPacketQueue");
213
214    virtual ~ReqPacketQueue() { }
215
216    const std::string name() const
217    { return masterPort.name() + "-" + label; }
218
219    bool sendTiming(PacketPtr pkt);
220
221};
222
223class SnoopRespPacketQueue : public PacketQueue
224{
225
226  protected:
227
228    MasterPort& masterPort;
229
230  public:
231
232    /**
233     * Create a snoop response packet queue, linked to an event
234     * manager, a master port, and a label that will be used for
235     * functional print request packets.
236     *
237     * @param _em Event manager used for scheduling this queue
238     * @param _masterPort Master port used to send the packets
239     * @param _label Label to push on the label stack for print request packets
240     */
241    SnoopRespPacketQueue(EventManager& _em, MasterPort& _masterPort,
242                         const std::string _label = "SnoopRespPacketQueue");
243
244    virtual ~SnoopRespPacketQueue() { }
245
246    const std::string name() const
247    { return masterPort.name() + "-" + label; }
248
249    bool sendTiming(PacketPtr pkt);
250
251};
252
253class RespPacketQueue : public PacketQueue
254{
255
256  protected:
257
258    SlavePort& slavePort;
259
260  public:
261
262    /**
263     * Create a response packet queue, linked to an event manager, a
264     * slave port, and a label that will be used for functional print
265     * request packets.
266     *
267     * @param _em Event manager used for scheduling this queue
268     * @param _slavePort Slave port used to send the packets
269     * @param _label Label to push on the label stack for print request packets
270     */
271    RespPacketQueue(EventManager& _em, SlavePort& _slavePort,
272                     const std::string _label = "RespPacketQueue");
273
274    virtual ~RespPacketQueue() { }
275
276    const std::string name() const
277    { return slavePort.name() + "-" + label; }
278
279    bool sendTiming(PacketPtr pkt);
280
281};
282
283#endif // __MEM_PACKET_QUEUE_HH__
284