packet_queue.hh revision 11207:7b7e352f8d7f 
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     /*
93      * Optionally disable the sanity check
94      * on the size of the transmitList. The
95      * sanity check will be enabled by default.
96      */
97    bool _disableSanityCheck;
98
99  protected:
100
101    /** Label to use for print request packets label stack. */
102    const std::string label;
103
104    /** Remember whether we're awaiting a retry. */
105    bool waitingOnRetry;
106
107    /** Check whether we have a packet ready to go on the transmit list. */
108    bool deferredPacketReady() const
109    { return !transmitList.empty() && transmitList.front().tick <= curTick(); }
110
111    /**
112     * Attempt to send a packet. Note that a subclass of the
113     * PacketQueue can override this method and thus change the
114     * behaviour (as done by the cache for the request queue). The
115     * default implementation sends the head of the transmit list. The
116     * caller must guarantee that the list is non-empty and that the
117     * head packet is scheduled for curTick() (or earlier).
118     */
119    virtual void sendDeferredPacket();
120
121    /**
122     * Send a packet using the appropriate method for the specific
123     * subclass (reuest, response or snoop response).
124     */
125    virtual bool sendTiming(PacketPtr pkt) = 0;
126
127    /**
128     * Create a packet queue, linked to an event manager, and a label
129     * that will be used for functional print request packets.
130     *
131     * @param _em Event manager used for scheduling this queue
132     * @param _label Label to push on the label stack for print request packets
133     * @param disable_sanity_check Flag used to disable the sanity check
134     *        on the size of the transmitList. The check is enabled by default.
135     */
136    PacketQueue(EventManager& _em, const std::string& _label,
137                bool disable_sanity_check = false);
138
139    /**
140     * Virtual desctructor since the class may be used as a base class.
141     */
142    virtual ~PacketQueue();
143
144  public:
145
146    /**
147     * Provide a name to simplify debugging.
148     *
149     * @return A complete name, appended to module and port
150     */
151    virtual const std::string name() const = 0;
152
153    /**
154     * Get the size of the queue.
155     */
156    size_t size() const { return transmitList.size(); }
157
158    /**
159     * Get the next packet ready time.
160     */
161    Tick deferredPacketReadyTime() const
162    { return transmitList.empty() ? MaxTick : transmitList.front().tick; }
163
164    /**
165     * Check if a packets address exists in the queue.
166     */
167    bool hasAddr(Addr addr) const;
168
169    /** Check the list of buffered packets against the supplied
170     * functional request. */
171    bool checkFunctional(PacketPtr pkt);
172
173    /**
174     * Schedule a send event if we are not already waiting for a
175     * retry. If the requested time is before an already scheduled
176     * send event, the event will be rescheduled. If MaxTick is
177     * passed, no event is scheduled. Instead, if we are idle and
178     * asked to drain then check and signal drained.
179     *
180     * @param when time to schedule an event
181     */
182    void schedSendEvent(Tick when);
183
184    /**
185     * Add a packet to the transmit list, and schedule a send event.
186     *
187     * @param pkt Packet to send
188     * @param when Absolute time (in ticks) to send packet
189     * @param force_order Force insertion order for packets with same address
190     */
191    void schedSendTiming(PacketPtr pkt, Tick when, bool force_order = false);
192
193    /**
194     * Retry sending a packet from the queue. Note that this is not
195     * necessarily the same packet if something has been added with an
196     * earlier time stamp.
197     */
198    void retry();
199
200    /**
201      * This allows a user to explicitly disable the sanity check
202      * on the size of the transmitList, which is enabled by default.
203      * Users must use this function to explicitly disable the sanity
204      * check.
205      */
206    void disableSanityCheck() { _disableSanityCheck = true; }
207
208    DrainState drain() override;
209};
210
211class ReqPacketQueue : public PacketQueue
212{
213
214  protected:
215
216    MasterPort& masterPort;
217
218  public:
219
220    /**
221     * Create a request packet queue, linked to an event manager, a
222     * master port, and a label that will be used for functional print
223     * request packets.
224     *
225     * @param _em Event manager used for scheduling this queue
226     * @param _masterPort Master port used to send the packets
227     * @param _label Label to push on the label stack for print request packets
228     */
229    ReqPacketQueue(EventManager& _em, MasterPort& _masterPort,
230                   const std::string _label = "ReqPacketQueue");
231
232    virtual ~ReqPacketQueue() { }
233
234    const std::string name() const
235    { return masterPort.name() + "-" + label; }
236
237    bool sendTiming(PacketPtr pkt);
238
239};
240
241class SnoopRespPacketQueue : public PacketQueue
242{
243
244  protected:
245
246    MasterPort& masterPort;
247
248  public:
249
250    /**
251     * Create a snoop response packet queue, linked to an event
252     * manager, a master port, and a label that will be used for
253     * functional print request packets.
254     *
255     * @param _em Event manager used for scheduling this queue
256     * @param _masterPort Master port used to send the packets
257     * @param _label Label to push on the label stack for print request packets
258     */
259    SnoopRespPacketQueue(EventManager& _em, MasterPort& _masterPort,
260                         const std::string _label = "SnoopRespPacketQueue");
261
262    virtual ~SnoopRespPacketQueue() { }
263
264    const std::string name() const
265    { return masterPort.name() + "-" + label; }
266
267    bool sendTiming(PacketPtr pkt);
268
269};
270
271class RespPacketQueue : public PacketQueue
272{
273
274  protected:
275
276    SlavePort& slavePort;
277
278  public:
279
280    /**
281     * Create a response packet queue, linked to an event manager, a
282     * slave port, and a label that will be used for functional print
283     * request packets.
284     *
285     * @param _em Event manager used for scheduling this queue
286     * @param _slavePort Slave port used to send the packets
287     * @param _label Label to push on the label stack for print request packets
288     */
289    RespPacketQueue(EventManager& _em, SlavePort& _slavePort,
290                     const std::string _label = "RespPacketQueue");
291
292    virtual ~RespPacketQueue() { }
293
294    const std::string name() const
295    { return slavePort.name() + "-" + label; }
296
297    bool sendTiming(PacketPtr pkt);
298
299};
300
301#endif // __MEM_PACKET_QUEUE_HH__
302