Topology.cc revision 10086:bd1089db3a88 
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
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27 */
28
29#include <cassert>
30
31#include "base/trace.hh"
32#include "debug/RubyNetwork.hh"
33#include "mem/ruby/common/NetDest.hh"
34#include "mem/ruby/network/BasicLink.hh"
35#include "mem/ruby/network/Topology.hh"
36#include "mem/ruby/slicc_interface/AbstractController.hh"
37
38using namespace std;
39
40const int INFINITE_LATENCY = 10000; // Yes, this is a big hack
41
42// Note: In this file, we use the first 2*m_nodes SwitchIDs to
43// represent the input and output endpoint links.  These really are
44// not 'switches', as they will not have a Switch object allocated for
45// them. The first m_nodes SwitchIDs are the links into the network,
46// the second m_nodes set of SwitchIDs represent the the output queues
47// of the network.
48
49// Helper functions based on chapter 29 of Cormen et al.
50void extend_shortest_path(Matrix& current_dist, Matrix& latencies,
51    Matrix& inter_switches);
52Matrix shortest_path(const Matrix& weights, Matrix& latencies,
53    Matrix& inter_switches);
54bool link_is_shortest_path_to_node(SwitchID src, SwitchID next,
55    SwitchID final, const Matrix& weights, const Matrix& dist);
56NetDest shortest_path_to_node(SwitchID src, SwitchID next,
57    const Matrix& weights, const Matrix& dist);
58
59Topology::Topology(uint32_t num_routers, vector<BasicExtLink *> ext_links,
60                   vector<BasicIntLink *> int_links)
61    : m_number_of_switches(num_routers)
62{
63
64    // initialize component latencies record
65    m_component_latencies.resize(0);
66    m_component_inter_switches.resize(0);
67
68    // Total nodes/controllers in network
69    // Must make sure this is called after the State Machine constructors
70    m_nodes = MachineType_base_number(MachineType_NUM);
71    assert(m_nodes > 1);
72
73    if (m_nodes != ext_links.size()) {
74        fatal("m_nodes (%d) != ext_links vector length (%d)\n",
75              m_nodes, ext_links.size());
76    }
77
78    // analyze both the internal and external links, create data structures
79    // Note that the python created links are bi-directional, but that the
80    // topology and networks utilize uni-directional links.  Thus each
81    // BasicLink is converted to two calls to add link, on for each direction
82    for (vector<BasicExtLink*>::const_iterator i = ext_links.begin();
83         i != ext_links.end(); ++i) {
84        BasicExtLink *ext_link = (*i);
85        AbstractController *abs_cntrl = ext_link->params()->ext_node;
86        BasicRouter *router = ext_link->params()->int_node;
87
88        // Store the ExtLink pointers for later
89        m_ext_link_vector.push_back(ext_link);
90
91        int machine_base_idx = MachineType_base_number(abs_cntrl->getType());
92        int ext_idx1 = machine_base_idx + abs_cntrl->getVersion();
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)
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<SwitchID, SwitchID> 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 =
183                        shortest_path_to_node(i, j, topology_weights, dist);
184                makeLink(net, i, j, destination_set);
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)
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, routing_table_entry);
224    } else if (dest < 2*m_nodes) {
225        assert(dest >= m_nodes);
226        NodeID node = dest - m_nodes;
227        src_dest.first = src;
228        src_dest.second = dest;
229        link_entry = m_link_map[src_dest];
230        net->makeOutLink(src - (2 * m_nodes), node, link_entry.link,
231                         link_entry.direction, routing_table_entry);
232    } else {
233        assert((src >= 2 * m_nodes) && (dest >= 2 * m_nodes));
234        src_dest.first = src;
235        src_dest.second = dest;
236        link_entry = m_link_map[src_dest];
237        net->makeInternalLink(src - (2 * m_nodes), dest - (2 * m_nodes),
238                              link_entry.link, link_entry.direction,
239                              routing_table_entry);
240    }
241}
242
243// The following all-pairs shortest path algorithm is based on the
244// discussion from Cormen et al., Chapter 26.1.
245void
246extend_shortest_path(Matrix& current_dist, Matrix& latencies,
247    Matrix& inter_switches)
248{
249    bool change = true;
250    int nodes = current_dist.size();
251
252    while (change) {
253        change = false;
254        for (int i = 0; i < nodes; i++) {
255            for (int j = 0; j < nodes; j++) {
256                int minimum = current_dist[i][j];
257                int previous_minimum = minimum;
258                int intermediate_switch = -1;
259                for (int k = 0; k < nodes; k++) {
260                    minimum = min(minimum,
261                        current_dist[i][k] + current_dist[k][j]);
262                    if (previous_minimum != minimum) {
263                        intermediate_switch = k;
264                        inter_switches[i][j] =
265                            inter_switches[i][k] +
266                            inter_switches[k][j] + 1;
267                    }
268                    previous_minimum = minimum;
269                }
270                if (current_dist[i][j] != minimum) {
271                    change = true;
272                    current_dist[i][j] = minimum;
273                    assert(intermediate_switch >= 0);
274                    assert(intermediate_switch < latencies[i].size());
275                    latencies[i][j] = latencies[i][intermediate_switch] +
276                        latencies[intermediate_switch][j];
277                }
278            }
279        }
280    }
281}
282
283Matrix
284shortest_path(const Matrix& weights, Matrix& latencies, Matrix& inter_switches)
285{
286    Matrix dist = weights;
287    extend_shortest_path(dist, latencies, inter_switches);
288    return dist;
289}
290
291bool
292link_is_shortest_path_to_node(SwitchID src, SwitchID next, SwitchID final,
293    const Matrix& weights, const Matrix& dist)
294{
295    return weights[src][next] + dist[next][final] == dist[src][final];
296}
297
298NetDest
299shortest_path_to_node(SwitchID src, SwitchID next, const Matrix& weights,
300    const Matrix& dist)
301{
302    NetDest result;
303    int d = 0;
304    int machines;
305    int max_machines;
306
307    machines = MachineType_NUM;
308    max_machines = MachineType_base_number(MachineType_NUM);
309
310    for (int m = 0; m < machines; m++) {
311        for (NodeID i = 0; i < MachineType_base_count((MachineType)m); i++) {
312            // we use "d+max_machines" below since the "destination"
313            // switches for the machines are numbered
314            // [MachineType_base_number(MachineType_NUM)...
315            //  2*MachineType_base_number(MachineType_NUM)-1] for the
316            // component network
317            if (link_is_shortest_path_to_node(src, next, d + max_machines,
318                    weights, dist)) {
319                MachineID mach = {(MachineType)m, i};
320                result.add(mach);
321            }
322            d++;
323        }
324    }
325
326    DPRINTF(RubyNetwork, "Returning shortest path\n"
327            "(src-(2*max_machines)): %d, (next-(2*max_machines)): %d, "
328            "src: %d, next: %d, result: %s\n",
329            (src-(2*max_machines)), (next-(2*max_machines)),
330            src, next, result);
331
332    return result;
333}
334