Topology.cc revision 10005:8c2b0dc16ccd 
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/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 machine_base_idx = MachineType_base_number(
93                string_to_MachineType(abs_cntrl->getName()));
94        int ext_idx1 = machine_base_idx + abs_cntrl->getVersion();
95        int ext_idx2 = ext_idx1 + m_nodes;
96        int int_idx = router->params()->router_id + 2*m_nodes;
97
98        // create the internal uni-directional links in both directions
99        //   the first direction is marked: In
100        addLink(ext_idx1, int_idx, ext_link, LinkDirection_In);
101        //   the first direction is marked: Out
102        addLink(int_idx, ext_idx2, ext_link, LinkDirection_Out);
103    }
104
105    for (vector<BasicIntLink*>::const_iterator i = int_links.begin();
106         i != int_links.end(); ++i) {
107        BasicIntLink *int_link = (*i);
108        BasicRouter *router_a = int_link->params()->node_a;
109        BasicRouter *router_b = int_link->params()->node_b;
110
111        // Store the IntLink pointers for later
112        m_int_link_vector.push_back(int_link);
113
114        int a = router_a->params()->router_id + 2*m_nodes;
115        int b = router_b->params()->router_id + 2*m_nodes;
116
117        // create the internal uni-directional links in both directions
118        //   the first direction is marked: In
119        addLink(a, b, int_link, LinkDirection_In);
120        //   the second direction is marked: Out
121        addLink(b, a, int_link, LinkDirection_Out);
122    }
123}
124
125void
126Topology::createLinks(Network *net)
127{
128    // Find maximum switchID
129    SwitchID max_switch_id = 0;
130    for (LinkMap::const_iterator i = m_link_map.begin();
131         i != m_link_map.end(); ++i) {
132        std::pair<SwitchID, SwitchID> src_dest = (*i).first;
133        max_switch_id = max(max_switch_id, src_dest.first);
134        max_switch_id = max(max_switch_id, src_dest.second);
135    }
136
137    // Initialize weight, latency, and inter switched vectors
138    Matrix topology_weights;
139    int num_switches = max_switch_id+1;
140    topology_weights.resize(num_switches);
141    m_component_latencies.resize(num_switches);
142    m_component_inter_switches.resize(num_switches);
143
144    for (int i = 0; i < topology_weights.size(); i++) {
145        topology_weights[i].resize(num_switches);
146        m_component_latencies[i].resize(num_switches);
147        m_component_inter_switches[i].resize(num_switches);
148
149        for (int j = 0; j < topology_weights[i].size(); j++) {
150            topology_weights[i][j] = INFINITE_LATENCY;
151
152            // initialize to invalid values
153            m_component_latencies[i][j] = -1;
154
155            // initially assume direct connections / no intermediate
156            // switches between components
157            m_component_inter_switches[i][j] = 0;
158        }
159    }
160
161    // Set identity weights to zero
162    for (int i = 0; i < topology_weights.size(); i++) {
163        topology_weights[i][i] = 0;
164    }
165
166    // Fill in the topology weights and bandwidth multipliers
167    for (LinkMap::const_iterator i = m_link_map.begin();
168         i != m_link_map.end(); ++i) {
169        std::pair<int, int> src_dest = (*i).first;
170        BasicLink* link = (*i).second.link;
171        int src = src_dest.first;
172        int dst = src_dest.second;
173        m_component_latencies[src][dst] = link->m_latency;
174        topology_weights[src][dst] = link->m_weight;
175    }
176
177    // Walk topology and hookup the links
178    Matrix dist = shortest_path(topology_weights, m_component_latencies,
179        m_component_inter_switches);
180    for (int i = 0; i < topology_weights.size(); i++) {
181        for (int j = 0; j < topology_weights[i].size(); j++) {
182            int weight = topology_weights[i][j];
183            if (weight > 0 && weight != INFINITE_LATENCY) {
184                NetDest destination_set =
185                        shortest_path_to_node(i, j, topology_weights, dist);
186                makeLink(net, i, j, destination_set);
187            }
188        }
189    }
190}
191
192void
193Topology::addLink(SwitchID src, SwitchID dest, BasicLink* link,
194                  LinkDirection dir)
195{
196    assert(src <= m_number_of_switches+m_nodes+m_nodes);
197    assert(dest <= m_number_of_switches+m_nodes+m_nodes);
198
199    std::pair<int, int> src_dest_pair;
200    LinkEntry link_entry;
201
202    src_dest_pair.first = src;
203    src_dest_pair.second = dest;
204    link_entry.direction = dir;
205    link_entry.link = link;
206    m_link_map[src_dest_pair] = link_entry;
207}
208
209void
210Topology::makeLink(Network *net, SwitchID src, SwitchID dest,
211                   const NetDest& routing_table_entry)
212{
213    // Make sure we're not trying to connect two end-point nodes
214    // directly together
215    assert(src >= 2 * m_nodes || dest >= 2 * m_nodes);
216
217    std::pair<int, int> src_dest;
218    LinkEntry link_entry;
219
220    if (src < m_nodes) {
221        src_dest.first = src;
222        src_dest.second = dest;
223        link_entry = m_link_map[src_dest];
224        net->makeInLink(src, dest - (2 * m_nodes), link_entry.link,
225                        link_entry.direction, routing_table_entry);
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, routing_table_entry);
234    } else {
235        assert((src >= 2 * m_nodes) && (dest >= 2 * m_nodes));
236        src_dest.first = src;
237        src_dest.second = dest;
238        link_entry = m_link_map[src_dest];
239        net->makeInternalLink(src - (2 * m_nodes), dest - (2 * m_nodes),
240                              link_entry.link, link_entry.direction,
241                              routing_table_entry);
242    }
243}
244
245// The following all-pairs shortest path algorithm is based on the
246// discussion from Cormen et al., Chapter 26.1.
247void
248extend_shortest_path(Matrix& current_dist, Matrix& latencies,
249    Matrix& inter_switches)
250{
251    bool change = true;
252    int nodes = current_dist.size();
253
254    while (change) {
255        change = false;
256        for (int i = 0; i < nodes; i++) {
257            for (int j = 0; j < nodes; j++) {
258                int minimum = current_dist[i][j];
259                int previous_minimum = minimum;
260                int intermediate_switch = -1;
261                for (int k = 0; k < nodes; k++) {
262                    minimum = min(minimum,
263                        current_dist[i][k] + current_dist[k][j]);
264                    if (previous_minimum != minimum) {
265                        intermediate_switch = k;
266                        inter_switches[i][j] =
267                            inter_switches[i][k] +
268                            inter_switches[k][j] + 1;
269                    }
270                    previous_minimum = minimum;
271                }
272                if (current_dist[i][j] != minimum) {
273                    change = true;
274                    current_dist[i][j] = minimum;
275                    assert(intermediate_switch >= 0);
276                    assert(intermediate_switch < latencies[i].size());
277                    latencies[i][j] = latencies[i][intermediate_switch] +
278                        latencies[intermediate_switch][j];
279                }
280            }
281        }
282    }
283}
284
285Matrix
286shortest_path(const Matrix& weights, Matrix& latencies, Matrix& inter_switches)
287{
288    Matrix dist = weights;
289    extend_shortest_path(dist, latencies, inter_switches);
290    return dist;
291}
292
293bool
294link_is_shortest_path_to_node(SwitchID src, SwitchID next, SwitchID final,
295    const Matrix& weights, const Matrix& dist)
296{
297    return weights[src][next] + dist[next][final] == dist[src][final];
298}
299
300NetDest
301shortest_path_to_node(SwitchID src, SwitchID next, const Matrix& weights,
302    const Matrix& dist)
303{
304    NetDest result;
305    int d = 0;
306    int machines;
307    int max_machines;
308
309    machines = MachineType_NUM;
310    max_machines = MachineType_base_number(MachineType_NUM);
311
312    for (int m = 0; m < machines; m++) {
313        for (NodeID i = 0; i < MachineType_base_count((MachineType)m); i++) {
314            // we use "d+max_machines" below since the "destination"
315            // switches for the machines are numbered
316            // [MachineType_base_number(MachineType_NUM)...
317            //  2*MachineType_base_number(MachineType_NUM)-1] for the
318            // component network
319            if (link_is_shortest_path_to_node(src, next, d + max_machines,
320                    weights, dist)) {
321                MachineID mach = {(MachineType)m, i};
322                result.add(mach);
323            }
324            d++;
325        }
326    }
327
328    DPRINTF(RubyNetwork, "Returning shortest path\n"
329            "(src-(2*max_machines)): %d, (next-(2*max_machines)): %d, "
330            "src: %d, next: %d, result: %s\n",
331            (src-(2*max_machines)), (next-(2*max_machines)),
332            src, next, result);
333
334    return result;
335}
336