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