src/mem/ruby/network/garnet/fixed-pipeline/SWallocator_d.cc

   1 /*
   2  * Copyright (c) 2008 Princeton University
   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  * Authors: Niket Agarwal
  29  */
  30
  31 #include "mem/ruby/network/garnet/fixed-pipeline/GarnetNetwork_d.hh"
  32 #include "mem/ruby/network/garnet/fixed-pipeline/InputUnit_d.hh"
  33 #include "mem/ruby/network/garnet/fixed-pipeline/OutputUnit_d.hh"
  34 #include "mem/ruby/network/garnet/fixed-pipeline/Router_d.hh"
  35 #include "mem/ruby/network/garnet/fixed-pipeline/SWallocator_d.hh"
  36
  37 SWallocator_d::SWallocator_d(Router_d *router)
  38     : Consumer(router)
  39 {
  40     m_router = router;
  41     m_num_vcs = m_router->get_num_vcs();
  42     m_vc_per_vnet = m_router->get_vc_per_vnet();
  43
  44     m_local_arbiter_activity = 0;
  45     m_global_arbiter_activity = 0;
  46 }
  47
  48 void
  49 SWallocator_d::init()
  50 {
  51     m_input_unit = m_router->get_inputUnit_ref();
  52     m_output_unit = m_router->get_outputUnit_ref();
  53
  54     m_num_inports = m_router->get_num_inports();
  55     m_num_outports = m_router->get_num_outports();
  56     m_round_robin_outport.resize(m_num_outports);
  57     m_round_robin_inport.resize(m_num_inports);
  58     m_port_req.resize(m_num_outports);
  59     m_vc_winners.resize(m_num_outports);
  60
  61     for (int i = 0; i < m_num_inports; i++) {
  62         m_round_robin_inport[i] = 0;
  63     }
  64
  65     for (int i = 0; i < m_num_outports; i++) {
  66         m_port_req[i].resize(m_num_inports);
  67         m_vc_winners[i].resize(m_num_inports);
  68
  69         m_round_robin_outport[i] = 0;
  70
  71         for (int j = 0; j < m_num_inports; j++) {
  72             m_port_req[i][j] = false; // [outport][inport]
  73         }
  74     }
  75 }
  76
  77 void
  78 SWallocator_d::wakeup()
  79 {
  80     arbitrate_inports(); // First stage of allocation
  81     arbitrate_outports(); // Second stage of allocation
  82
  83     clear_request_vector();
  84     check_for_wakeup();
  85     m_router->call_switch();
  86
  87 }
  88
  89 void
  90 SWallocator_d::arbitrate_inports()
  91 {
  92     // First do round robin arbitration on a set of input vc requests
  93     for (int inport = 0; inport < m_num_inports; inport++) {
  94         int invc = m_round_robin_inport[inport];
  95
  96         // Select next round robin vc candidate within valid vnet
  97         int next_round_robin_invc = invc;
  98         do {
  99             next_round_robin_invc++;
 100
 101             if (next_round_robin_invc >= m_num_vcs)
 102                 next_round_robin_invc = 0;
 103         } while (!((m_router->get_net_ptr())->validVirtualNetwork(
 104                     get_vnet(next_round_robin_invc))));
 105
 106         m_round_robin_inport[inport] = next_round_robin_invc;
 107
 108         for (int invc_iter = 0; invc_iter < m_num_vcs; invc_iter++) {
 109             invc++;
 110             if (invc >= m_num_vcs)
 111                 invc = 0;
 112
 113             if (!((m_router->get_net_ptr())->validVirtualNetwork(
 114                 get_vnet(invc))))
 115                 continue;
 116
 117             if (m_input_unit[inport]->need_stage(invc, ACTIVE_, SA_,
 118                                                  m_router->curCycle()) &&
 119                 m_input_unit[inport]->has_credits(invc)) {
 120
 121                 if (is_candidate_inport(inport, invc)) {
 122                     int outport = m_input_unit[inport]->get_route(invc);
 123                     m_local_arbiter_activity++;
 124                     m_port_req[outport][inport] = true;
 125                     m_vc_winners[outport][inport]= invc;
 126                     break; // got one vc winner for this port
 127                 }
 128             }
 129         }
 130     }
 131 }
 132
 133 bool
 134 SWallocator_d::is_candidate_inport(int inport, int invc)
 135 {
 136     int outport = m_input_unit[inport]->get_route(invc);
 137     Cycles t_enqueue_time = m_input_unit[inport]->get_enqueue_time(invc);
 138     int t_vnet = get_vnet(invc);
 139     int vc_base = t_vnet*m_vc_per_vnet;
 140     if ((m_router->get_net_ptr())->isVNetOrdered(t_vnet)) {
 141         for (int vc_offset = 0; vc_offset < m_vc_per_vnet; vc_offset++) {
 142             int temp_vc = vc_base + vc_offset;
 143             if (m_input_unit[inport]->need_stage(temp_vc, ACTIVE_, SA_,
 144                                                  m_router->curCycle()) &&
 145                (m_input_unit[inport]->get_route(temp_vc) == outport) &&
 146                (m_input_unit[inport]->get_enqueue_time(temp_vc) <
 147                     t_enqueue_time)) {
 148                 return false;
 149                 break;
 150             }
 151         }
 152     }
 153     return true;
 154 }
 155
 156
 157 void
 158 SWallocator_d::arbitrate_outports()
 159 {
 160     // Now there are a set of input vc requests for output vcs.
 161     // Again do round robin arbitration on these requests
 162     for (int outport = 0; outport < m_num_outports; outport++) {
 163         int inport = m_round_robin_outport[outport];
 164         m_round_robin_outport[outport]++;
 165
 166         if (m_round_robin_outport[outport] >= m_num_outports)
 167             m_round_robin_outport[outport] = 0;
 168
 169         for (int inport_iter = 0; inport_iter < m_num_inports; inport_iter++) {
 170             inport++;
 171             if (inport >= m_num_inports)
 172                 inport = 0;
 173
 174             // inport has a request this cycle for outport:
 175             if (m_port_req[outport][inport]) {
 176                 m_port_req[outport][inport] = false;
 177                 int invc = m_vc_winners[outport][inport];
 178                 int outvc = m_input_unit[inport]->get_outvc(invc);
 179
 180                 // remove flit from Input Unit
 181                 flit_d *t_flit = m_input_unit[inport]->getTopFlit(invc);
 182                 t_flit->advance_stage(ST_, m_router->curCycle());
 183                 t_flit->set_vc(outvc);
 184                 t_flit->set_outport(outport);
 185                 t_flit->set_time(m_router->curCycle());
 186
 187                 m_output_unit[outport]->decrement_credit(outvc);
 188                 m_router->update_sw_winner(inport, t_flit);
 189                 m_global_arbiter_activity++;
 190
 191                 if ((t_flit->get_type() == TAIL_) ||
 192                     t_flit->get_type() == HEAD_TAIL_) {
 193
 194                     // Send a credit back
 195                     // along with the information that this VC is now idle
 196                     m_input_unit[inport]->increment_credit(invc, true,
 197                         m_router->curCycle());
 198
 199                     // This Input VC should now be empty
 200                     assert(m_input_unit[inport]->isReady(invc,
 201                         m_router->curCycle()) == false);
 202
 203                     m_input_unit[inport]->set_vc_state(IDLE_, invc,
 204                         m_router->curCycle());
 205                     m_input_unit[inport]->set_enqueue_time(invc,
 206                         Cycles(INFINITE_));
 207                 } else {
 208                     // Send a credit back
 209                     // but do not indicate that the VC is idle
 210                     m_input_unit[inport]->increment_credit(invc, false,
 211                         m_router->curCycle());
 212                 }
 213                 break; // got a in request for this outport
 214             }
 215         }
 216     }
 217 }
 218
 219 void
 220 SWallocator_d::check_for_wakeup()
 221 {
 222     Cycles nextCycle = m_router->curCycle() + Cycles(1);
 223
 224     for (int i = 0; i < m_num_inports; i++) {
 225         for (int j = 0; j < m_num_vcs; j++) {
 226             if (m_input_unit[i]->need_stage(j, ACTIVE_, SA_, nextCycle)) {
 227                 m_router->vcarb_req();
 228                 return;
 229             }
 230         }
 231     }
 232 }
 233
 234 int
 235 SWallocator_d::get_vnet(int invc)
 236 {
 237     int vnet = invc/m_vc_per_vnet;
 238     assert(vnet < m_router->get_num_vnets());
 239     return vnet;
 240 }
 241
 242 void
 243 SWallocator_d::clear_request_vector()
 244 {
 245     for (int i = 0; i < m_num_outports; i++) {
 246         for (int j = 0; j < m_num_inports; j++) {
 247             m_port_req[i][j] = false;
 248         }
 249     }
 250 }