RoutingUnit.cc revision 13449:2f7efa89c58b 
1/*
2 * Copyright (c) 2008 Princeton University
3 * Copyright (c) 2016 Georgia Institute of Technology
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met: redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer;
10 * redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution;
13 * neither the name of the copyright holders nor the names of its
14 * contributors may be used to endorse or promote products derived from
15 * this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * Authors: Niket Agarwal
30 *          Tushar Krishna
31 */
32
33
34#include "mem/ruby/network/garnet2.0/RoutingUnit.hh"
35
36#include "base/cast.hh"
37#include "base/logging.hh"
38#include "mem/ruby/network/garnet2.0/InputUnit.hh"
39#include "mem/ruby/network/garnet2.0/Router.hh"
40#include "mem/ruby/slicc_interface/Message.hh"
41
42RoutingUnit::RoutingUnit(Router *router)
43{
44    m_router = router;
45    m_routing_table.clear();
46    m_weight_table.clear();
47}
48
49void
50RoutingUnit::addRoute(const NetDest& routing_table_entry)
51{
52    m_routing_table.push_back(routing_table_entry);
53}
54
55void
56RoutingUnit::addWeight(int link_weight)
57{
58    m_weight_table.push_back(link_weight);
59}
60
61/*
62 * This is the default routing algorithm in garnet.
63 * The routing table is populated during topology creation.
64 * Routes can be biased via weight assignments in the topology file.
65 * Correct weight assignments are critical to provide deadlock avoidance.
66 */
67
68int
69RoutingUnit::lookupRoutingTable(int vnet, NetDest msg_destination)
70{
71    // First find all possible output link candidates
72    // For ordered vnet, just choose the first
73    // (to make sure different packets don't choose different routes)
74    // For unordered vnet, randomly choose any of the links
75    // To have a strict ordering between links, they should be given
76    // different weights in the topology file
77
78    int output_link = -1;
79    int min_weight = INFINITE_;
80    std::vector<int> output_link_candidates;
81    int num_candidates = 0;
82
83    // Identify the minimum weight among the candidate output links
84    for (int link = 0; link < m_routing_table.size(); link++) {
85        if (msg_destination.intersectionIsNotEmpty(m_routing_table[link])) {
86
87        if (m_weight_table[link] <= min_weight)
88            min_weight = m_weight_table[link];
89        }
90    }
91
92    // Collect all candidate output links with this minimum weight
93    for (int link = 0; link < m_routing_table.size(); link++) {
94        if (msg_destination.intersectionIsNotEmpty(m_routing_table[link])) {
95
96            if (m_weight_table[link] == min_weight) {
97
98                num_candidates++;
99                output_link_candidates.push_back(link);
100            }
101        }
102    }
103
104    if (output_link_candidates.size() == 0) {
105        fatal("Fatal Error:: No Route exists from this Router.");
106        exit(0);
107    }
108
109    // Randomly select any candidate output link
110    int candidate = 0;
111    if (!(m_router->get_net_ptr())->isVNetOrdered(vnet))
112        candidate = rand() % num_candidates;
113
114    output_link = output_link_candidates.at(candidate);
115    return output_link;
116}
117
118
119void
120RoutingUnit::addInDirection(PortDirection inport_dirn, int inport_idx)
121{
122    m_inports_dirn2idx[inport_dirn] = inport_idx;
123    m_inports_idx2dirn[inport_idx]  = inport_dirn;
124}
125
126void
127RoutingUnit::addOutDirection(PortDirection outport_dirn, int outport_idx)
128{
129    m_outports_dirn2idx[outport_dirn] = outport_idx;
130    m_outports_idx2dirn[outport_idx]  = outport_dirn;
131}
132
133// outportCompute() is called by the InputUnit
134// It calls the routing table by default.
135// A template for adaptive topology-specific routing algorithm
136// implementations using port directions rather than a static routing
137// table is provided here.
138
139int
140RoutingUnit::outportCompute(RouteInfo route, int inport,
141                            PortDirection inport_dirn)
142{
143    int outport = -1;
144
145    if (route.dest_router == m_router->get_id()) {
146
147        // Multiple NIs may be connected to this router,
148        // all with output port direction = "Local"
149        // Get exact outport id from table
150        outport = lookupRoutingTable(route.vnet, route.net_dest);
151        return outport;
152    }
153
154    // Routing Algorithm set in GarnetNetwork.py
155    // Can be over-ridden from command line using --routing-algorithm = 1
156    RoutingAlgorithm routing_algorithm =
157        (RoutingAlgorithm) m_router->get_net_ptr()->getRoutingAlgorithm();
158
159    switch (routing_algorithm) {
160        case TABLE_:  outport =
161            lookupRoutingTable(route.vnet, route.net_dest); break;
162        case XY_:     outport =
163            outportComputeXY(route, inport, inport_dirn); break;
164        // any custom algorithm
165        case CUSTOM_: outport =
166            outportComputeCustom(route, inport, inport_dirn); break;
167        default: outport =
168            lookupRoutingTable(route.vnet, route.net_dest); break;
169    }
170
171    assert(outport != -1);
172    return outport;
173}
174
175// XY routing implemented using port directions
176// Only for reference purpose in a Mesh
177// By default Garnet uses the routing table
178int
179RoutingUnit::outportComputeXY(RouteInfo route,
180                              int inport,
181                              PortDirection inport_dirn)
182{
183    PortDirection outport_dirn = "Unknown";
184
185    int M5_VAR_USED num_rows = m_router->get_net_ptr()->getNumRows();
186    int num_cols = m_router->get_net_ptr()->getNumCols();
187    assert(num_rows > 0 && num_cols > 0);
188
189    int my_id = m_router->get_id();
190    int my_x = my_id % num_cols;
191    int my_y = my_id / num_cols;
192
193    int dest_id = route.dest_router;
194    int dest_x = dest_id % num_cols;
195    int dest_y = dest_id / num_cols;
196
197    int x_hops = abs(dest_x - my_x);
198    int y_hops = abs(dest_y - my_y);
199
200    bool x_dirn = (dest_x >= my_x);
201    bool y_dirn = (dest_y >= my_y);
202
203    // already checked that in outportCompute() function
204    assert(!(x_hops == 0 && y_hops == 0));
205
206    if (x_hops > 0) {
207        if (x_dirn) {
208            assert(inport_dirn == "Local" || inport_dirn == "West");
209            outport_dirn = "East";
210        } else {
211            assert(inport_dirn == "Local" || inport_dirn == "East");
212            outport_dirn = "West";
213        }
214    } else if (y_hops > 0) {
215        if (y_dirn) {
216            // "Local" or "South" or "West" or "East"
217            assert(inport_dirn != "North");
218            outport_dirn = "North";
219        } else {
220            // "Local" or "North" or "West" or "East"
221            assert(inport_dirn != "South");
222            outport_dirn = "South";
223        }
224    } else {
225        // x_hops == 0 and y_hops == 0
226        // this is not possible
227        // already checked that in outportCompute() function
228        panic("x_hops == y_hops == 0");
229    }
230
231    return m_outports_dirn2idx[outport_dirn];
232}
233
234// Template for implementing custom routing algorithm
235// using port directions. (Example adaptive)
236int
237RoutingUnit::outportComputeCustom(RouteInfo route,
238                                 int inport,
239                                 PortDirection inport_dirn)
240{
241    panic("%s placeholder executed", __FUNCTION__);
242}
243