packet_queue.hh revision 13564 
1/*
2 * Copyright (c) 2012,2015,2018 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    EventFunctionWrapper 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    /**
100     * if true, inserted packets have to be unconditionally scheduled
101     * after the last packet in the queue that references the same
102     * address
103     */
104    bool forceOrder;
105
106  protected:
107
108    /** Label to use for print request packets label stack. */
109    const std::string label;
110
111    /** Remember whether we're awaiting a retry. */
112    bool waitingOnRetry;
113
114    /** Check whether we have a packet ready to go on the transmit list. */
115    bool deferredPacketReady() const
116    { return !transmitList.empty() && transmitList.front().tick <= curTick(); }
117
118    /**
119     * Attempt to send a packet. Note that a subclass of the
120     * PacketQueue can override this method and thus change the
121     * behaviour (as done by the cache for the request queue). The
122     * default implementation sends the head of the transmit list. The
123     * caller must guarantee that the list is non-empty and that the
124     * head packet is scheduled for curTick() (or earlier).
125     */
126    virtual void sendDeferredPacket();
127
128    /**
129     * Send a packet using the appropriate method for the specific
130     * subclass (reuest, response or snoop response).
131     */
132    virtual bool sendTiming(PacketPtr pkt) = 0;
133
134    /**
135     * Create a packet queue, linked to an event manager, and a label
136     * that will be used for functional print request packets.
137     *
138     * @param _em Event manager used for scheduling this queue
139     * @param _label Label to push on the label stack for print request packets
140     * @param force_order Force insertion order for packets with same address
141     * @param disable_sanity_check Flag used to disable the sanity check
142     *        on the size of the transmitList. The check is enabled by default.
143     */
144    PacketQueue(EventManager& _em, const std::string& _label,
145                const std::string& _sendEventName,
146                bool force_order = false,
147                bool disable_sanity_check = false);
148
149    /**
150     * Virtual desctructor since the class may be used as a base class.
151     */
152    virtual ~PacketQueue();
153
154  public:
155
156    /**
157     * Provide a name to simplify debugging.
158     *
159     * @return A complete name, appended to module and port
160     */
161    virtual const std::string name() const = 0;
162
163    /**
164     * Get the size of the queue.
165     */
166    size_t size() const { return transmitList.size(); }
167
168    /**
169     * Get the next packet ready time.
170     */
171    Tick deferredPacketReadyTime() const
172    { return transmitList.empty() ? MaxTick : transmitList.front().tick; }
173
174    /**
175     * Check if a packets address exists in the queue.
176     */
177    bool hasAddr(Addr addr) const;
178
179    /** Check the list of buffered packets against the supplied
180     * functional request. */
181    bool trySatisfyFunctional(PacketPtr pkt);
182
183    /**
184     * Schedule a send event if we are not already waiting for a
185     * retry. If the requested time is before an already scheduled
186     * send event, the event will be rescheduled. If MaxTick is
187     * passed, no event is scheduled. Instead, if we are idle and
188     * asked to drain then check and signal drained.
189     *
190     * @param when time to schedule an event
191     */
192    void schedSendEvent(Tick when);
193
194    /**
195     * Add a packet to the transmit list, and schedule a send event.
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     * Retry sending a packet from the queue. Note that this is not
204     * necessarily the same packet if something has been added with an
205     * earlier time stamp.
206     */
207    void retry();
208
209    /**
210      * This allows a user to explicitly disable the sanity check
211      * on the size of the transmitList, which is enabled by default.
212      * Users must use this function to explicitly disable the sanity
213      * check.
214      */
215    void disableSanityCheck() { _disableSanityCheck = true; }
216
217    DrainState drain() override;
218};
219
220class ReqPacketQueue : public PacketQueue
221{
222
223  protected:
224
225    MasterPort& masterPort;
226
227    // Static definition so it can be called when constructing the parent
228    // without us being completely initialized.
229    static const std::string name(const MasterPort& masterPort,
230                                  const std::string& label)
231    { return masterPort.name() + "-" + label; }
232
233  public:
234
235    /**
236     * Create a request packet queue, linked to an event manager, a
237     * master port, and a label that will be used for functional print
238     * request packets.
239     *
240     * @param _em Event manager used for scheduling this queue
241     * @param _masterPort Master port used to send the packets
242     * @param _label Label to push on the label stack for print request packets
243     */
244    ReqPacketQueue(EventManager& _em, MasterPort& _masterPort,
245                   const std::string _label = "ReqPacketQueue");
246
247    virtual ~ReqPacketQueue() { }
248
249    const std::string name() const
250    { return name(masterPort, label); }
251
252    bool sendTiming(PacketPtr pkt);
253
254};
255
256class SnoopRespPacketQueue : public PacketQueue
257{
258
259  protected:
260
261    MasterPort& masterPort;
262
263    // Static definition so it can be called when constructing the parent
264    // without us being completely initialized.
265    static const std::string name(const MasterPort& masterPort,
266                                  const std::string& label)
267    { return masterPort.name() + "-" + label; }
268
269  public:
270
271    /**
272     * Create a snoop response packet queue, linked to an event
273     * manager, a master port, and a label that will be used for
274     * functional print request packets.
275     *
276     * @param _em Event manager used for scheduling this queue
277     * @param _masterPort Master port used to send the packets
278     * @param force_order Force insertion order for packets with same address
279     * @param _label Label to push on the label stack for print request packets
280     */
281    SnoopRespPacketQueue(EventManager& _em, MasterPort& _masterPort,
282                         bool force_order = false,
283                         const std::string _label = "SnoopRespPacketQueue");
284
285    virtual ~SnoopRespPacketQueue() { }
286
287    const std::string name() const
288    { return name(masterPort, label); }
289
290    bool sendTiming(PacketPtr pkt);
291
292};
293
294class RespPacketQueue : public PacketQueue
295{
296
297  protected:
298
299    SlavePort& slavePort;
300
301    // Static definition so it can be called when constructing the parent
302    // without us being completely initialized.
303    static const std::string name(const SlavePort& slavePort,
304                                  const std::string& label)
305    { return slavePort.name() + "-" + label; }
306
307  public:
308
309    /**
310     * Create a response packet queue, linked to an event manager, a
311     * slave port, and a label that will be used for functional print
312     * request packets.
313     *
314     * @param _em Event manager used for scheduling this queue
315     * @param _slavePort Slave port used to send the packets
316     * @param force_order Force insertion order for packets with same address
317     * @param _label Label to push on the label stack for print request packets
318     */
319    RespPacketQueue(EventManager& _em, SlavePort& _slavePort,
320                    bool force_order = false,
321                    const std::string _label = "RespPacketQueue");
322
323    virtual ~RespPacketQueue() { }
324
325    const std::string name() const
326    { return name(slavePort, label); }
327
328    bool sendTiming(PacketPtr pkt);
329
330};
331
332#endif // __MEM_PACKET_QUEUE_HH__
333