PerfectSwitch.cc revision 11037:91d6a2d95cf8 
1/*
2 * Copyright (c) 1999-2008 Mark D. Hill and David A. Wood
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
29#include <algorithm>
30
31#include "base/cast.hh"
32#include "base/random.hh"
33#include "debug/RubyNetwork.hh"
34#include "mem/ruby/network/MessageBuffer.hh"
35#include "mem/ruby/network/simple/PerfectSwitch.hh"
36#include "mem/ruby/network/simple/SimpleNetwork.hh"
37#include "mem/ruby/network/simple/Switch.hh"
38#include "mem/ruby/slicc_interface/Message.hh"
39
40using namespace std;
41
42const int PRIORITY_SWITCH_LIMIT = 128;
43
44// Operator for helper class
45bool
46operator<(const LinkOrder& l1, const LinkOrder& l2)
47{
48    return (l1.m_value < l2.m_value);
49}
50
51PerfectSwitch::PerfectSwitch(SwitchID sid, Switch *sw, uint32_t virt_nets)
52    : Consumer(sw), m_switch_id(sid), m_switch(sw)
53{
54    m_round_robin_start = 0;
55    m_wakeups_wo_switch = 0;
56    m_virtual_networks = virt_nets;
57}
58
59void
60PerfectSwitch::init(SimpleNetwork *network_ptr)
61{
62    m_network_ptr = network_ptr;
63
64    for(int i = 0;i < m_virtual_networks;++i) {
65        m_pending_message_count.push_back(0);
66    }
67}
68
69void
70PerfectSwitch::addInPort(const vector<MessageBuffer*>& in)
71{
72    NodeID port = m_in.size();
73    m_in.push_back(in);
74
75    for (int i = 0; i < in.size(); ++i) {
76        if (in[i] != nullptr) {
77            in[i]->setConsumer(this);
78            in[i]->setIncomingLink(port);
79            in[i]->setVnet(i);
80        }
81    }
82}
83
84void
85PerfectSwitch::addOutPort(const vector<MessageBuffer*>& out,
86                          const NetDest& routing_table_entry)
87{
88    // Setup link order
89    LinkOrder l;
90    l.m_value = 0;
91    l.m_link = m_out.size();
92    m_link_order.push_back(l);
93
94    // Add to routing table
95    m_out.push_back(out);
96    m_routing_table.push_back(routing_table_entry);
97}
98
99PerfectSwitch::~PerfectSwitch()
100{
101}
102
103void
104PerfectSwitch::operateVnet(int vnet)
105{
106    // This is for round-robin scheduling
107    int incoming = m_round_robin_start;
108    m_round_robin_start++;
109    if (m_round_robin_start >= m_in.size()) {
110        m_round_robin_start = 0;
111    }
112
113    if(m_pending_message_count[vnet] > 0) {
114        // for all input ports, use round robin scheduling
115        for (int counter = 0; counter < m_in.size(); counter++) {
116            // Round robin scheduling
117            incoming++;
118            if (incoming >= m_in.size()) {
119                incoming = 0;
120            }
121
122            // Is there a message waiting?
123            if (m_in[incoming].size() <= vnet) {
124                continue;
125            }
126
127            MessageBuffer *buffer = m_in[incoming][vnet];
128            if (buffer == nullptr) {
129                continue;
130            }
131
132            operateMessageBuffer(buffer, incoming, vnet);
133        }
134    }
135}
136
137void
138PerfectSwitch::operateMessageBuffer(MessageBuffer *buffer, int incoming,
139                                    int vnet)
140{
141    MsgPtr msg_ptr;
142    Message *net_msg_ptr = NULL;
143
144    // temporary vectors to store the routing results
145    vector<LinkID> output_links;
146    vector<NetDest> output_link_destinations;
147
148    while (buffer->isReady()) {
149        DPRINTF(RubyNetwork, "incoming: %d\n", incoming);
150
151        // Peek at message
152        msg_ptr = buffer->peekMsgPtr();
153        net_msg_ptr = msg_ptr.get();
154        DPRINTF(RubyNetwork, "Message: %s\n", (*net_msg_ptr));
155
156        output_links.clear();
157        output_link_destinations.clear();
158        NetDest msg_dsts = net_msg_ptr->getDestination();
159
160        // Unfortunately, the token-protocol sends some
161        // zero-destination messages, so this assert isn't valid
162        // assert(msg_dsts.count() > 0);
163
164        assert(m_link_order.size() == m_routing_table.size());
165        assert(m_link_order.size() == m_out.size());
166
167        if (m_network_ptr->getAdaptiveRouting()) {
168            if (m_network_ptr->isVNetOrdered(vnet)) {
169                // Don't adaptively route
170                for (int out = 0; out < m_out.size(); out++) {
171                    m_link_order[out].m_link = out;
172                    m_link_order[out].m_value = 0;
173                }
174            } else {
175                // Find how clogged each link is
176                for (int out = 0; out < m_out.size(); out++) {
177                    int out_queue_length = 0;
178                    for (int v = 0; v < m_virtual_networks; v++) {
179                        out_queue_length += m_out[out][v]->getSize();
180                    }
181                    int value =
182                        (out_queue_length << 8) |
183                        random_mt.random(0, 0xff);
184                    m_link_order[out].m_link = out;
185                    m_link_order[out].m_value = value;
186                }
187
188                // Look at the most empty link first
189                sort(m_link_order.begin(), m_link_order.end());
190            }
191        }
192
193        for (int i = 0; i < m_routing_table.size(); i++) {
194            // pick the next link to look at
195            int link = m_link_order[i].m_link;
196            NetDest dst = m_routing_table[link];
197            DPRINTF(RubyNetwork, "dst: %s\n", dst);
198
199            if (!msg_dsts.intersectionIsNotEmpty(dst))
200                continue;
201
202            // Remember what link we're using
203            output_links.push_back(link);
204
205            // Need to remember which destinations need this message in
206            // another vector.  This Set is the intersection of the
207            // routing_table entry and the current destination set.  The
208            // intersection must not be empty, since we are inside "if"
209            output_link_destinations.push_back(msg_dsts.AND(dst));
210
211            // Next, we update the msg_destination not to include
212            // those nodes that were already handled by this link
213            msg_dsts.removeNetDest(dst);
214        }
215
216        assert(msg_dsts.count() == 0);
217
218        // Check for resources - for all outgoing queues
219        bool enough = true;
220        for (int i = 0; i < output_links.size(); i++) {
221            int outgoing = output_links[i];
222
223            if (!m_out[outgoing][vnet]->areNSlotsAvailable(1))
224                enough = false;
225
226            DPRINTF(RubyNetwork, "Checking if node is blocked ..."
227                    "outgoing: %d, vnet: %d, enough: %d\n",
228                    outgoing, vnet, enough);
229        }
230
231        // There were not enough resources
232        if (!enough) {
233            scheduleEvent(Cycles(1));
234            DPRINTF(RubyNetwork, "Can't deliver message since a node "
235                    "is blocked\n");
236            DPRINTF(RubyNetwork, "Message: %s\n", (*net_msg_ptr));
237            break; // go to next incoming port
238        }
239
240        MsgPtr unmodified_msg_ptr;
241
242        if (output_links.size() > 1) {
243            // If we are sending this message down more than one link
244            // (size>1), we need to make a copy of the message so each
245            // branch can have a different internal destination we need
246            // to create an unmodified MsgPtr because the MessageBuffer
247            // enqueue func will modify the message
248
249            // This magic line creates a private copy of the message
250            unmodified_msg_ptr = msg_ptr->clone();
251        }
252
253        // Dequeue msg
254        buffer->dequeue();
255        m_pending_message_count[vnet]--;
256
257        // Enqueue it - for all outgoing queues
258        for (int i=0; i<output_links.size(); i++) {
259            int outgoing = output_links[i];
260
261            if (i > 0) {
262                // create a private copy of the unmodified message
263                msg_ptr = unmodified_msg_ptr->clone();
264            }
265
266            // Change the internal destination set of the message so it
267            // knows which destinations this link is responsible for.
268            net_msg_ptr = msg_ptr.get();
269            net_msg_ptr->getDestination() = output_link_destinations[i];
270
271            // Enqeue msg
272            DPRINTF(RubyNetwork, "Enqueuing net msg from "
273                    "inport[%d][%d] to outport [%d][%d].\n",
274                    incoming, vnet, outgoing, vnet);
275
276            m_out[outgoing][vnet]->enqueue(msg_ptr);
277        }
278    }
279}
280
281void
282PerfectSwitch::wakeup()
283{
284    // Give the highest numbered link priority most of the time
285    m_wakeups_wo_switch++;
286    int highest_prio_vnet = m_virtual_networks-1;
287    int lowest_prio_vnet = 0;
288    int decrementer = 1;
289
290    // invert priorities to avoid starvation seen in the component network
291    if (m_wakeups_wo_switch > PRIORITY_SWITCH_LIMIT) {
292        m_wakeups_wo_switch = 0;
293        highest_prio_vnet = 0;
294        lowest_prio_vnet = m_virtual_networks-1;
295        decrementer = -1;
296    }
297
298    // For all components incoming queues
299    for (int vnet = highest_prio_vnet;
300         (vnet * decrementer) >= (decrementer * lowest_prio_vnet);
301         vnet -= decrementer) {
302        operateVnet(vnet);
303    }
304}
305
306void
307PerfectSwitch::storeEventInfo(int info)
308{
309    m_pending_message_count[info]++;
310}
311
312void
313PerfectSwitch::clearStats()
314{
315}
316void
317PerfectSwitch::collateStats()
318{
319}
320
321
322void
323PerfectSwitch::print(std::ostream& out) const
324{
325    out << "[PerfectSwitch " << m_switch_id << "]";
326}
327