packet_queue.cc revision 4492 
1/*
2 * Copyright (c) 2006 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Ali Saidi
29 */
30
31#include "mem/tport.hh"
32
33void
34SimpleTimingPort::checkFunctional(PacketPtr pkt)
35{
36    DeferredPacketIterator i = transmitList.begin();
37    DeferredPacketIterator end = transmitList.end();
38
39    for (; i != end; ++i) {
40        PacketPtr target = i->pkt;
41        // If the target contains data, and it overlaps the
42        // probed request, need to update data
43        if (target->intersect(pkt)) {
44            if (!fixPacket(pkt, target)) {
45                // fixPacket returns true for continue, false for done
46                return;
47            }
48        }
49    }
50}
51
52void
53SimpleTimingPort::recvFunctional(PacketPtr pkt)
54{
55    checkFunctional(pkt);
56
57    // Just do an atomic access and throw away the returned latency
58    if (pkt->result != Packet::Success)
59        recvAtomic(pkt);
60}
61
62bool
63SimpleTimingPort::recvTiming(PacketPtr pkt)
64{
65    // If the device is only a slave, it should only be sending
66    // responses, which should never get nacked.  There used to be
67    // code to hanldle nacks here, but I'm pretty sure it didn't work
68    // correctly with the drain code, so that would need to be fixed
69    // if we ever added it back.
70    assert(pkt->result != Packet::Nacked);
71    Tick latency = recvAtomic(pkt);
72    // turn packet around to go back to requester if response expected
73    if (pkt->needsResponse()) {
74        pkt->makeTimingResponse();
75        schedSendTiming(pkt, latency);
76    }
77    else if (pkt->cmd != MemCmd::UpgradeReq) {
78        delete pkt->req;
79        delete pkt;
80    }
81    return true;
82}
83
84
85void
86SimpleTimingPort::schedSendTiming(PacketPtr pkt, Tick when)
87{
88    assert(when > curTick);
89
90    // Nothing is on the list: add it and schedule an event
91    if (transmitList.empty()) {
92        assert(!sendEvent->scheduled());
93        sendEvent->schedule(when);
94        transmitList.push_back(DeferredPacket(when, pkt));
95        return;
96    }
97
98    // something is on the list and this belongs at the end
99    if (when >= transmitList.back().tick) {
100        transmitList.push_back(DeferredPacket(when, pkt));
101        return;
102    }
103    // Something is on the list and this belongs somewhere else
104    DeferredPacketIterator i = transmitList.begin();
105    DeferredPacketIterator end = transmitList.end();
106
107    for (; i != end; ++i) {
108        if (when < i->tick) {
109            if (i == transmitList.begin()) {
110                //Inserting at begining, reschedule
111                sendEvent->reschedule(when);
112            }
113            transmitList.insert(i, DeferredPacket(when, pkt));
114            return;
115        }
116    }
117    assert(false); // should never get here
118}
119
120
121void
122SimpleTimingPort::sendDeferredPacket()
123{
124    assert(deferredPacketReady());
125    bool success = sendTiming(transmitList.front().pkt);
126
127    if (success) {
128        //send successful, remove packet
129        transmitList.pop_front();
130        if (!transmitList.empty()) {
131            Tick time = transmitList.front().tick;
132            sendEvent->schedule(time <= curTick ? curTick+1 : time);
133        }
134
135        if (transmitList.empty() && drainEvent) {
136            drainEvent->process();
137            drainEvent = NULL;
138        }
139    }
140
141    waitingOnRetry = !success;
142
143    if (waitingOnRetry) {
144        DPRINTF(Bus, "Send failed, waiting on retry\n");
145    }
146}
147
148
149void
150SimpleTimingPort::recvRetry()
151{
152    DPRINTF(Bus, "Received retry\n");
153    assert(waitingOnRetry);
154    sendDeferredPacket();
155}
156
157
158void
159SimpleTimingPort::processSendEvent()
160{
161    assert(!waitingOnRetry);
162    sendDeferredPacket();
163}
164
165
166unsigned int
167SimpleTimingPort::drain(Event *de)
168{
169    if (transmitList.size() == 0)
170        return 0;
171    drainEvent = de;
172    return 1;
173}
174