xref: /gem5/src/mem/ruby/network/Topology.cc

/*
 * Copyright (c) 1999-2008 Mark D. Hill and David A. Wood
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Topology.cc
 *
 * Description: See Topology.hh
 *
 * $Id$
 *
 * */

#include "mem/ruby/network/simple/Topology.hh"
#include "mem/ruby/common/NetDest.hh"
#include "mem/ruby/network/Network.hh"
#include "mem/ruby/slicc_interface/AbstractController.hh"
#include "mem/protocol/TopologyType.hh"
#include "mem/gems_common/util.hh"
#include "mem/protocol/MachineType.hh"
#include "mem/protocol/Protocol.hh"
#include "mem/ruby/system/System.hh"
#include <string>

static const int INFINITE_LATENCY = 10000; // Yes, this is a big hack
static const int DEFAULT_BW_MULTIPLIER = 1;  // Just to be consistent with above :)

// Note: In this file, we use the first 2*m_nodes SwitchIDs to
// represent the input and output endpoint links.  These really are
// not 'switches', as they will not have a Switch object allocated for
// them. The first m_nodes SwitchIDs are the links into the network,
// the second m_nodes set of SwitchIDs represent the the output queues
// of the network.

// Helper functions based on chapter 29 of Cormen et al.
static void extend_shortest_path(Matrix& current_dist, Matrix& latencies, Matrix& inter_switches);
static Matrix shortest_path(const Matrix& weights, Matrix& latencies, Matrix& inter_switches);
static bool link_is_shortest_path_to_node(SwitchID src, SwitchID next, SwitchID final, const Matrix& weights, const Matrix& dist);
static NetDest shortest_path_to_node(SwitchID src, SwitchID next, const Matrix& weights, const Matrix& dist);

Topology::Topology(const Params *p)
    : SimObject(p)
{
    m_print_config = p->print_config;
    m_number_of_switches = p->num_int_nodes;
    // initialize component latencies record
    m_component_latencies.setSize(0);
    m_component_inter_switches.setSize(0);

    //
    // Total nodes/controllers in network
    // Must make sure this is called after the State Machine constructors
    //
    m_nodes = MachineType_base_number(MachineType_NUM);
    assert(m_nodes > 1);

    if (m_nodes != params()->ext_links.size()) {
        fatal("m_nodes (%d) != ext_links vector length (%d)\n",
              m_nodes != params()->ext_links.size());
    }

    //
    // First create the links between the endpoints (i.e. controllers) and the
    // network.
    //
  for (vector<ExtLink*>::const_iterator i = params()->ext_links.begin();
       i != params()->ext_links.end(); ++i)
  {
      const ExtLinkParams *p = (*i)->params();
      AbstractController *c = p->ext_node;

      // Store the controller pointers for later
      m_controller_vector.insertAtBottom(c);

      int ext_idx1 =
          MachineType_base_number(c->getMachineType()) + c->getVersion();
      int ext_idx2 = ext_idx1 + m_nodes;
      int int_idx = p->int_node + 2*m_nodes;

      // create the links in both directions
      addLink(ext_idx1, int_idx, p->latency, p->bw_multiplier, p->weight);
      addLink(int_idx, ext_idx2, p->latency, p->bw_multiplier, p->weight);
  }

  for (vector<IntLink*>::const_iterator i = params()->int_links.begin();
       i != params()->int_links.end(); ++i)
  {
      const IntLinkParams *p = (*i)->params();
      int a = p->node_a + 2*m_nodes;
      int b = p->node_b + 2*m_nodes;

      // create the links in both directions
      addLink(a, b, p->latency, p->bw_multiplier, p->weight);
      addLink(b, a, p->latency, p->bw_multiplier, p->weight);
  }
}


void Topology::initNetworkPtr(Network* net_ptr)
{
    for (int cntrl = 0; cntrl < m_controller_vector.size(); cntrl++)
    {
        m_controller_vector[cntrl]->initNetworkPtr(net_ptr);
    }
}


void Topology::createLinks(Network *net, bool isReconfiguration)
{
  // Find maximum switchID

  SwitchID max_switch_id = 0;
  for (int i=0; i<m_links_src_vector.size(); i++) {
    max_switch_id = max(max_switch_id, m_links_src_vector[i]);
    max_switch_id = max(max_switch_id, m_links_dest_vector[i]);
  }

  // Initialize weight vector
  Matrix topology_weights;
  Matrix topology_latency;
  Matrix topology_bw_multis;
  int num_switches = max_switch_id+1;
  topology_weights.setSize(num_switches);
  topology_latency.setSize(num_switches);
  topology_bw_multis.setSize(num_switches);
  m_component_latencies.setSize(num_switches);  // FIXME setting the size of a member variable here is a HACK!
  m_component_inter_switches.setSize(num_switches);  // FIXME setting the size of a member variable here is a HACK!
  for(int i=0; i<topology_weights.size(); i++) {
    topology_weights[i].setSize(num_switches);
    topology_latency[i].setSize(num_switches);
    topology_bw_multis[i].setSize(num_switches);
    m_component_latencies[i].setSize(num_switches);
    m_component_inter_switches[i].setSize(num_switches);  // FIXME setting the size of a member variable here is a HACK!
    for(int j=0; j<topology_weights[i].size(); j++) {
      topology_weights[i][j] = INFINITE_LATENCY;
      topology_latency[i][j] = -1;  // initialize to an invalid value
      topology_bw_multis[i][j] = -1;  // initialize to an invalid value
      m_component_latencies[i][j] = -1; // initialize to an invalid value
      m_component_inter_switches[i][j] = 0;  // initially assume direct connections / no intermediate switches between components
    }
  }

  // Set identity weights to zero
  for(int i=0; i<topology_weights.size(); i++) {
    topology_weights[i][i] = 0;
  }

  // Fill in the topology weights and bandwidth multipliers
  for (int i=0; i<m_links_src_vector.size(); i++) {
    topology_weights[m_links_src_vector[i]][m_links_dest_vector[i]] = m_links_weight_vector[i];
    topology_latency[m_links_src_vector[i]][m_links_dest_vector[i]] = m_links_latency_vector[i];
    m_component_latencies[m_links_src_vector[i]][m_links_dest_vector[i]] = m_links_latency_vector[i];  // initialize to latency vector
    topology_bw_multis[m_links_src_vector[i]][m_links_dest_vector[i]] = m_bw_multiplier_vector[i];
  }

  // Walk topology and hookup the links
  Matrix dist = shortest_path(topology_weights, m_component_latencies, m_component_inter_switches);
  for(int i=0; i<topology_weights.size(); i++) {
    for(int j=0; j<topology_weights[i].size(); j++) {
      int weight = topology_weights[i][j];
      int bw_multiplier = topology_bw_multis[i][j];
      int latency = topology_latency[i][j];
      if (weight > 0 && weight != INFINITE_LATENCY) {
        NetDest destination_set = shortest_path_to_node(i, j, topology_weights, dist);
        assert(latency != -1);
        makeLink(net, i, j, destination_set, latency, weight, bw_multiplier, isReconfiguration);
      }
    }
  }
}

SwitchID Topology::newSwitchID()
{
  m_number_of_switches++;
  return m_number_of_switches-1+m_nodes+m_nodes;
}

void Topology::addLink(SwitchID src, SwitchID dest, int link_latency)
{
  addLink(src, dest, link_latency, DEFAULT_BW_MULTIPLIER, link_latency);
}

void Topology::addLink(SwitchID src, SwitchID dest, int link_latency, int bw_multiplier)
{
  addLink(src, dest, link_latency, bw_multiplier, link_latency);
}

void Topology::addLink(SwitchID src, SwitchID dest, int link_latency, int bw_multiplier, int link_weight)
{
  ASSERT(src <= m_number_of_switches+m_nodes+m_nodes);
  ASSERT(dest <= m_number_of_switches+m_nodes+m_nodes);
  m_links_src_vector.insertAtBottom(src);
  m_links_dest_vector.insertAtBottom(dest);
  m_links_latency_vector.insertAtBottom(link_latency);
  m_links_weight_vector.insertAtBottom(link_weight);
  m_bw_multiplier_vector.insertAtBottom(bw_multiplier);
}

void Topology::makeLink(Network *net, SwitchID src, SwitchID dest, const NetDest& routing_table_entry, int link_latency, int link_weight, int bw_multiplier, bool isReconfiguration)
{
  // Make sure we're not trying to connect two end-point nodes directly together
  assert((src >= 2*m_nodes) || (dest >= 2*m_nodes));

  if (src < m_nodes) {
    net->makeInLink(src, dest-(2*m_nodes), routing_table_entry, link_latency, bw_multiplier, isReconfiguration);
  } else if (dest < 2*m_nodes) {
    assert(dest >= m_nodes);
    NodeID node = dest-m_nodes;
    net->makeOutLink(src-(2*m_nodes), node, routing_table_entry, link_latency, link_weight, bw_multiplier, isReconfiguration);
  } else {
    assert((src >= 2*m_nodes) && (dest >= 2*m_nodes));
    net->makeInternalLink(src-(2*m_nodes), dest-(2*m_nodes), routing_table_entry, link_latency, link_weight, bw_multiplier, isReconfiguration);
  }
}

void Topology::printConfig(ostream& out) const
{
  if (m_print_config == false) return;

  assert(m_component_latencies.size() > 0);

  out << "--- Begin Topology Print ---" << endl;
  out << endl;
  out << "Topology print ONLY indicates the _NETWORK_ latency between two machines" << endl;
  out << "It does NOT include the latency within the machines" << endl;
  out << endl;
  for (int m=0; m<MachineType_NUM; m++) {
    for (int i=0; i<MachineType_base_count((MachineType)m); i++) {
      MachineID cur_mach = {(MachineType)m, i};
      out << cur_mach << " Network Latencies" << endl;
      for (int n=0; n<MachineType_NUM; n++) {
        for (int j=0; j<MachineType_base_count((MachineType)n); j++) {
          MachineID dest_mach = {(MachineType)n, j};
          if (cur_mach != dest_mach) {
            int link_latency = m_component_latencies[MachineType_base_number((MachineType)m)+i][MachineType_base_number(MachineType_NUM)+MachineType_base_number((MachineType)n)+j];
            int intermediate_switches = m_component_inter_switches[MachineType_base_number((MachineType)m)+i][MachineType_base_number(MachineType_NUM)+MachineType_base_number((MachineType)n)+j];
            out << "  " << cur_mach << " -> " << dest_mach << " net_lat: "
                << link_latency+intermediate_switches << endl;  // NOTE switches are assumed to have single cycle latency
          }
        }
      }
      out << endl;
    }
  }

  out << "--- End Topology Print ---" << endl;
}

/**************************************************************************/

// The following all-pairs shortest path algorithm is based on the
// discussion from Cormen et al., Chapter 26.1.

static void extend_shortest_path(Matrix& current_dist, Matrix& latencies, Matrix& inter_switches)
{
  bool change = true;
  int nodes = current_dist.size();

  while (change) {
    change = false;
    for (int i=0; i<nodes; i++) {
      for (int j=0; j<nodes; j++) {
        int minimum = current_dist[i][j];
        int previous_minimum = minimum;
        int intermediate_switch = -1;
        for (int k=0; k<nodes; k++) {
          minimum = min(minimum, current_dist[i][k] + current_dist[k][j]);
          if (previous_minimum != minimum) {
            intermediate_switch = k;
            inter_switches[i][j] = inter_switches[i][k] + inter_switches[k][j] + 1;
          }
          previous_minimum = minimum;
        }
        if (current_dist[i][j] != minimum) {
          change = true;
          current_dist[i][j] = minimum;
          assert(intermediate_switch >= 0);
          assert(intermediate_switch < latencies[i].size());
          latencies[i][j] = latencies[i][intermediate_switch] + latencies[intermediate_switch][j];
        }
      }
    }
  }
}

static Matrix shortest_path(const Matrix& weights, Matrix& latencies, Matrix& inter_switches)
{
  Matrix dist = weights;
  extend_shortest_path(dist, latencies, inter_switches);
  return dist;
}

static bool link_is_shortest_path_to_node(SwitchID src, SwitchID next, SwitchID final,
                                          const Matrix& weights, const Matrix& dist)
{
  return (weights[src][next] + dist[next][final] == dist[src][final]);
}

static NetDest shortest_path_to_node(SwitchID src, SwitchID next,
                                     const Matrix& weights, const Matrix& dist)
{
  NetDest result;
  int d = 0;
  int machines;
  int max_machines;

  machines = MachineType_NUM;
  max_machines = MachineType_base_number(MachineType_NUM);

  for (int m=0; m<machines; m++) {
    for (int i=0; i<MachineType_base_count((MachineType)m); i++) {
      // we use "d+max_machines" below since the "destination" switches for the machines are numbered
      // [MachineType_base_number(MachineType_NUM)...2*MachineType_base_number(MachineType_NUM)-1]
      // for the component network
      if (link_is_shortest_path_to_node(src, next,
                                        d+max_machines,
                                        weights, dist)) {
        MachineID mach = {(MachineType)m, i};
        result.add(mach);
      }
      d++;
    }
  }

  DEBUG_MSG(NETWORK_COMP, MedPrio, "returning shortest path");
  DEBUG_EXPR(NETWORK_COMP, MedPrio, (src-(2*max_machines)));
  DEBUG_EXPR(NETWORK_COMP, MedPrio, (next-(2*max_machines)));
  DEBUG_EXPR(NETWORK_COMP, MedPrio, src);
  DEBUG_EXPR(NETWORK_COMP, MedPrio, next);
  DEBUG_EXPR(NETWORK_COMP, MedPrio, result);
  DEBUG_NEWLINE(NETWORK_COMP, MedPrio);

  return result;
}

Topology *
TopologyParams::create()
{
    return new Topology(this);
}

Link *
LinkParams::create()
{
    return new Link(this);
}

ExtLink *
ExtLinkParams::create()
{
    return new ExtLink(this);
}

IntLink *
IntLinkParams::create()
{
    return new IntLink(this);
}