Topology.cc revision 9594:219ad5fe8c04 
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 <cassert>
30
31#include "base/trace.hh"
32#include "debug/RubyNetwork.hh"
33#include "mem/protocol/MachineType.hh"
34#include "mem/ruby/common/NetDest.hh"
35#include "mem/ruby/network/BasicLink.hh"
36#include "mem/ruby/network/Topology.hh"
37#include "mem/ruby/slicc_interface/AbstractController.hh"
38
39using namespace std;
40
41const int INFINITE_LATENCY = 10000; // Yes, this is a big hack
42
43// Note: In this file, we use the first 2*m_nodes SwitchIDs to
44// represent the input and output endpoint links.  These really are
45// not 'switches', as they will not have a Switch object allocated for
46// them. The first m_nodes SwitchIDs are the links into the network,
47// the second m_nodes set of SwitchIDs represent the the output queues
48// of the network.
49
50// Helper functions based on chapter 29 of Cormen et al.
51void extend_shortest_path(Matrix& current_dist, Matrix& latencies,
52    Matrix& inter_switches);
53Matrix shortest_path(const Matrix& weights, Matrix& latencies,
54    Matrix& inter_switches);
55bool link_is_shortest_path_to_node(SwitchID src, SwitchID next,
56    SwitchID final, const Matrix& weights, const Matrix& dist);
57NetDest shortest_path_to_node(SwitchID src, SwitchID next,
58    const Matrix& weights, const Matrix& dist);
59
60Topology::Topology(uint32_t num_routers, vector<BasicExtLink *> ext_links,
61                   vector<BasicIntLink *> int_links)
62    : m_number_of_switches(num_routers)
63{
64
65    // initialize component latencies record
66    m_component_latencies.resize(0);
67    m_component_inter_switches.resize(0);
68
69    // Total nodes/controllers in network
70    // Must make sure this is called after the State Machine constructors
71    m_nodes = MachineType_base_number(MachineType_NUM);
72    assert(m_nodes > 1);
73
74    if (m_nodes != ext_links.size()) {
75        fatal("m_nodes (%d) != ext_links vector length (%d)\n",
76              m_nodes, ext_links.size());
77    }
78
79    // analyze both the internal and external links, create data structures
80    // Note that the python created links are bi-directional, but that the
81    // topology and networks utilize uni-directional links.  Thus each
82    // BasicLink is converted to two calls to add link, on for each direction
83    for (vector<BasicExtLink*>::const_iterator i = ext_links.begin();
84         i != ext_links.end(); ++i) {
85        BasicExtLink *ext_link = (*i);
86        AbstractController *abs_cntrl = ext_link->params()->ext_node;
87        BasicRouter *router = ext_link->params()->int_node;
88
89        // Store the ExtLink pointers for later
90        m_ext_link_vector.push_back(ext_link);
91
92        int ext_idx1 = abs_cntrl->params()->cntrl_id;
93        int ext_idx2 = ext_idx1 + m_nodes;
94        int int_idx = router->params()->router_id + 2*m_nodes;
95
96        // create the internal uni-directional links in both directions
97        //   the first direction is marked: In
98        addLink(ext_idx1, int_idx, ext_link, LinkDirection_In);
99        //   the first direction is marked: Out
100        addLink(int_idx, ext_idx2, ext_link, LinkDirection_Out);
101    }
102
103    for (vector<BasicIntLink*>::const_iterator i = int_links.begin();
104         i != int_links.end(); ++i) {
105        BasicIntLink *int_link = (*i);
106        BasicRouter *router_a = int_link->params()->node_a;
107        BasicRouter *router_b = int_link->params()->node_b;
108
109        // Store the IntLink pointers for later
110        m_int_link_vector.push_back(int_link);
111
112        int a = router_a->params()->router_id + 2*m_nodes;
113        int b = router_b->params()->router_id + 2*m_nodes;
114
115        // create the internal uni-directional links in both directions
116        //   the first direction is marked: In
117        addLink(a, b, int_link, LinkDirection_In);
118        //   the second direction is marked: Out
119        addLink(b, a, int_link, LinkDirection_Out);
120    }
121}
122
123void
124Topology::createLinks(Network *net, bool isReconfiguration)
125{
126    // Find maximum switchID
127    SwitchID max_switch_id = 0;
128    for (LinkMap::const_iterator i = m_link_map.begin();
129         i != m_link_map.end(); ++i) {
130        std::pair<int, int> src_dest = (*i).first;
131        max_switch_id = max(max_switch_id, src_dest.first);
132        max_switch_id = max(max_switch_id, src_dest.second);
133    }
134
135    // Initialize weight, latency, and inter switched vectors
136    Matrix topology_weights;
137    int num_switches = max_switch_id+1;
138    topology_weights.resize(num_switches);
139    m_component_latencies.resize(num_switches);
140    m_component_inter_switches.resize(num_switches);
141
142    for (int i = 0; i < topology_weights.size(); i++) {
143        topology_weights[i].resize(num_switches);
144        m_component_latencies[i].resize(num_switches);
145        m_component_inter_switches[i].resize(num_switches);
146
147        for (int j = 0; j < topology_weights[i].size(); j++) {
148            topology_weights[i][j] = INFINITE_LATENCY;
149
150            // initialize to invalid values
151            m_component_latencies[i][j] = -1;
152
153            // initially assume direct connections / no intermediate
154            // switches between components
155            m_component_inter_switches[i][j] = 0;
156        }
157    }
158
159    // Set identity weights to zero
160    for (int i = 0; i < topology_weights.size(); i++) {
161        topology_weights[i][i] = 0;
162    }
163
164    // Fill in the topology weights and bandwidth multipliers
165    for (LinkMap::const_iterator i = m_link_map.begin();
166         i != m_link_map.end(); ++i) {
167        std::pair<int, int> src_dest = (*i).first;
168        BasicLink* link = (*i).second.link;
169        int src = src_dest.first;
170        int dst = src_dest.second;
171        m_component_latencies[src][dst] = link->m_latency;
172        topology_weights[src][dst] = link->m_weight;
173    }
174
175    // Walk topology and hookup the links
176    Matrix dist = shortest_path(topology_weights, m_component_latencies,
177        m_component_inter_switches);
178    for (int i = 0; i < topology_weights.size(); i++) {
179        for (int j = 0; j < topology_weights[i].size(); j++) {
180            int weight = topology_weights[i][j];
181            if (weight > 0 && weight != INFINITE_LATENCY) {
182                NetDest destination_set = shortest_path_to_node(i, j,
183                                                     topology_weights, dist);
184                makeLink(net, i, j, destination_set, isReconfiguration);
185            }
186        }
187    }
188}
189
190void
191Topology::addLink(SwitchID src, SwitchID dest, BasicLink* link,
192                  LinkDirection dir)
193{
194    assert(src <= m_number_of_switches+m_nodes+m_nodes);
195    assert(dest <= m_number_of_switches+m_nodes+m_nodes);
196
197    std::pair<int, int> src_dest_pair;
198    LinkEntry link_entry;
199
200    src_dest_pair.first = src;
201    src_dest_pair.second = dest;
202    link_entry.direction = dir;
203    link_entry.link = link;
204    m_link_map[src_dest_pair] = link_entry;
205}
206
207void
208Topology::makeLink(Network *net, SwitchID src, SwitchID dest,
209                   const NetDest& routing_table_entry, bool isReconfiguration)
210{
211    // Make sure we're not trying to connect two end-point nodes
212    // directly together
213    assert(src >= 2 * m_nodes || dest >= 2 * m_nodes);
214
215    std::pair<int, int> src_dest;
216    LinkEntry link_entry;
217
218    if (src < m_nodes) {
219        src_dest.first = src;
220        src_dest.second = dest;
221        link_entry = m_link_map[src_dest];
222        net->makeInLink(src, dest - (2 * m_nodes), link_entry.link,
223                        link_entry.direction,
224                        routing_table_entry,
225                        isReconfiguration);
226    } else if (dest < 2*m_nodes) {
227        assert(dest >= m_nodes);
228        NodeID node = dest - m_nodes;
229        src_dest.first = src;
230        src_dest.second = dest;
231        link_entry = m_link_map[src_dest];
232        net->makeOutLink(src - (2 * m_nodes), node, link_entry.link,
233                         link_entry.direction,
234                         routing_table_entry,
235                         isReconfiguration);
236    } else {
237        assert((src >= 2 * m_nodes) && (dest >= 2 * m_nodes));
238        src_dest.first = src;
239        src_dest.second = dest;
240        link_entry = m_link_map[src_dest];
241        net->makeInternalLink(src - (2 * m_nodes), dest - (2 * m_nodes),
242                              link_entry.link, link_entry.direction,
243                              routing_table_entry, isReconfiguration);
244    }
245}
246
247// The following all-pairs shortest path algorithm is based on the
248// discussion from Cormen et al., Chapter 26.1.
249void
250extend_shortest_path(Matrix& current_dist, Matrix& latencies,
251    Matrix& inter_switches)
252{
253    bool change = true;
254    int nodes = current_dist.size();
255
256    while (change) {
257        change = false;
258        for (int i = 0; i < nodes; i++) {
259            for (int j = 0; j < nodes; j++) {
260                int minimum = current_dist[i][j];
261                int previous_minimum = minimum;
262                int intermediate_switch = -1;
263                for (int k = 0; k < nodes; k++) {
264                    minimum = min(minimum,
265                        current_dist[i][k] + current_dist[k][j]);
266                    if (previous_minimum != minimum) {
267                        intermediate_switch = k;
268                        inter_switches[i][j] =
269                            inter_switches[i][k] +
270                            inter_switches[k][j] + 1;
271                    }
272                    previous_minimum = minimum;
273                }
274                if (current_dist[i][j] != minimum) {
275                    change = true;
276                    current_dist[i][j] = minimum;
277                    assert(intermediate_switch >= 0);
278                    assert(intermediate_switch < latencies[i].size());
279                    latencies[i][j] = latencies[i][intermediate_switch] +
280                        latencies[intermediate_switch][j];
281                }
282            }
283        }
284    }
285}
286
287Matrix
288shortest_path(const Matrix& weights, Matrix& latencies, Matrix& inter_switches)
289{
290    Matrix dist = weights;
291    extend_shortest_path(dist, latencies, inter_switches);
292    return dist;
293}
294
295bool
296link_is_shortest_path_to_node(SwitchID src, SwitchID next, SwitchID final,
297    const Matrix& weights, const Matrix& dist)
298{
299    return weights[src][next] + dist[next][final] == dist[src][final];
300}
301
302NetDest
303shortest_path_to_node(SwitchID src, SwitchID next, const Matrix& weights,
304    const Matrix& dist)
305{
306    NetDest result;
307    int d = 0;
308    int machines;
309    int max_machines;
310
311    machines = MachineType_NUM;
312    max_machines = MachineType_base_number(MachineType_NUM);
313
314    for (int m = 0; m < machines; m++) {
315        for (int i = 0; i < MachineType_base_count((MachineType)m); i++) {
316            // we use "d+max_machines" below since the "destination"
317            // switches for the machines are numbered
318            // [MachineType_base_number(MachineType_NUM)...
319            //  2*MachineType_base_number(MachineType_NUM)-1] for the
320            // component network
321            if (link_is_shortest_path_to_node(src, next, d + max_machines,
322                    weights, dist)) {
323                MachineID mach = {(MachineType)m, i};
324                result.add(mach);
325            }
326            d++;
327        }
328    }
329
330    DPRINTF(RubyNetwork, "Returning shortest path\n"
331            "(src-(2*max_machines)): %d, (next-(2*max_machines)): %d, "
332            "src: %d, next: %d, result: %s\n",
333            (src-(2*max_machines)), (next-(2*max_machines)),
334            src, next, result);
335
336    return result;
337}
338