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         next_round_robin_invc++;
  99         if (next_round_robin_invc >= m_num_vcs)
 100             next_round_robin_invc = 0;
 101         m_round_robin_inport[inport] = next_round_robin_invc;
 102
 103         for (int invc_iter = 0; invc_iter < m_num_vcs; invc_iter++) {
 104             invc++;
 105             if (invc >= m_num_vcs)
 106                 invc = 0;
 107
 108             if (m_input_unit[inport]->need_stage(invc, ACTIVE_, SA_,
 109                                                  m_router->curCycle()) &&
 110                 m_input_unit[inport]->has_credits(invc)) {
 111
 112                 if (is_candidate_inport(inport, invc)) {
 113                     int outport = m_input_unit[inport]->get_route(invc);
 114                     m_local_arbiter_activity++;
 115                     m_port_req[outport][inport] = true;
 116                     m_vc_winners[outport][inport]= invc;
 117                     break; // got one vc winner for this port
 118                 }
 119             }
 120         }
 121     }
 122 }
 123
 124 bool
 125 SWallocator_d::is_candidate_inport(int inport, int invc)
 126 {
 127     int outport = m_input_unit[inport]->get_route(invc);
 128     Cycles t_enqueue_time = m_input_unit[inport]->get_enqueue_time(invc);
 129     int t_vnet = get_vnet(invc);
 130     int vc_base = t_vnet*m_vc_per_vnet;
 131     if ((m_router->get_net_ptr())->isVNetOrdered(t_vnet)) {
 132         for (int vc_offset = 0; vc_offset < m_vc_per_vnet; vc_offset++) {
 133             int temp_vc = vc_base + vc_offset;
 134             if (m_input_unit[inport]->need_stage(temp_vc, ACTIVE_, SA_,
 135                                                  m_router->curCycle()) &&
 136                (m_input_unit[inport]->get_route(temp_vc) == outport) &&
 137                (m_input_unit[inport]->get_enqueue_time(temp_vc) <
 138                     t_enqueue_time)) {
 139                 return false;
 140                 break;
 141             }
 142         }
 143     }
 144     return true;
 145 }
 146
 147
 148 void
 149 SWallocator_d::arbitrate_outports()
 150 {
 151     // Now there are a set of input vc requests for output vcs.
 152     // Again do round robin arbitration on these requests
 153     for (int outport = 0; outport < m_num_outports; outport++) {
 154         int inport = m_round_robin_outport[outport];
 155         m_round_robin_outport[outport]++;
 156
 157         if (m_round_robin_outport[outport] >= m_num_outports)
 158             m_round_robin_outport[outport] = 0;
 159
 160         for (int inport_iter = 0; inport_iter < m_num_inports; inport_iter++) {
 161             inport++;
 162             if (inport >= m_num_inports)
 163                 inport = 0;
 164
 165             // inport has a request this cycle for outport:
 166             if (m_port_req[outport][inport]) {
 167                 m_port_req[outport][inport] = false;
 168                 int invc = m_vc_winners[outport][inport];
 169                 int outvc = m_input_unit[inport]->get_outvc(invc);
 170
 171                 // remove flit from Input Unit
 172                 flit_d *t_flit = m_input_unit[inport]->getTopFlit(invc);
 173                 t_flit->advance_stage(ST_, m_router->curCycle());
 174                 t_flit->set_vc(outvc);
 175                 t_flit->set_outport(outport);
 176                 t_flit->set_time(m_router->curCycle());
 177
 178                 m_output_unit[outport]->decrement_credit(outvc);
 179                 m_router->update_sw_winner(inport, t_flit);
 180                 m_global_arbiter_activity++;
 181
 182                 if ((t_flit->get_type() == TAIL_) ||
 183                     t_flit->get_type() == HEAD_TAIL_) {
 184
 185                     // Send a credit back
 186                     // along with the information that this VC is now idle
 187                     m_input_unit[inport]->increment_credit(invc, true,
 188                         m_router->curCycle());
 189
 190                     // This Input VC should now be empty
 191                     assert(m_input_unit[inport]->isReady(invc,
 192                         m_router->curCycle()) == false);
 193
 194                     m_input_unit[inport]->set_vc_state(IDLE_, invc,
 195                         m_router->curCycle());
 196                     m_input_unit[inport]->set_enqueue_time(invc,
 197                         Cycles(INFINITE_));
 198                 } else {
 199                     // Send a credit back
 200                     // but do not indicate that the VC is idle
 201                     m_input_unit[inport]->increment_credit(invc, false,
 202                         m_router->curCycle());
 203                 }
 204                 break; // got a in request for this outport
 205             }
 206         }
 207     }
 208 }
 209
 210 void
 211 SWallocator_d::check_for_wakeup()
 212 {
 213     Cycles nextCycle = m_router->curCycle() + Cycles(1);
 214
 215     for (int i = 0; i < m_num_inports; i++) {
 216         for (int j = 0; j < m_num_vcs; j++) {
 217             if (m_input_unit[i]->need_stage(j, ACTIVE_, SA_, nextCycle)) {
 218                 m_router->vcarb_req();
 219                 return;
 220             }
 221         }
 222     }
 223 }
 224
 225 int
 226 SWallocator_d::get_vnet(int invc)
 227 {
 228     int vnet = invc/m_vc_per_vnet;
 229     assert(vnet < m_router->get_num_vnets());
 230     return vnet;
 231 }
 232
 233 void
 234 SWallocator_d::clear_request_vector()
 235 {
 236     for (int i = 0; i < m_num_outports; i++) {
 237         for (int j = 0; j < m_num_inports; j++) {
 238             m_port_req[i][j] = false;
 239         }
 240     }
 241 }