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/*
* Copyright (c) 2008 Princeton University
* Copyright (c) 2016 Georgia Institute of Technology
* 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.
*
* Authors: Niket Agarwal
* Tushar Krishna
*/
#include "mem/ruby/network/garnet2.0/RoutingUnit.hh"
#include "base/cast.hh"
#include "base/logging.hh"
#include "mem/ruby/network/garnet2.0/InputUnit.hh"
#include "mem/ruby/network/garnet2.0/Router.hh"
#include "mem/ruby/slicc_interface/Message.hh"
RoutingUnit::RoutingUnit(Router *router)
{
m_router = router;
m_routing_table.clear();
m_weight_table.clear();
}
void
RoutingUnit::addRoute(const NetDest& routing_table_entry)
{
m_routing_table.push_back(routing_table_entry);
}
void
RoutingUnit::addWeight(int link_weight)
{
m_weight_table.push_back(link_weight);
}
/*
* This is the default routing algorithm in garnet.
* The routing table is populated during topology creation.
* Routes can be biased via weight assignments in the topology file.
* Correct weight assignments are critical to provide deadlock avoidance.
*/
int
RoutingUnit::lookupRoutingTable(int vnet, NetDest msg_destination)
{
// First find all possible output link candidates
// For ordered vnet, just choose the first
// (to make sure different packets don't choose different routes)
// For unordered vnet, randomly choose any of the links
// To have a strict ordering between links, they should be given
// different weights in the topology file
int output_link = -1;
int min_weight = INFINITE_;
std::vector<int> output_link_candidates;
int num_candidates = 0;
// Identify the minimum weight among the candidate output links
for (int link = 0; link < m_routing_table.size(); link++) {
if (msg_destination.intersectionIsNotEmpty(m_routing_table[link])) {
if (m_weight_table[link] <= min_weight)
min_weight = m_weight_table[link];
}
}
// Collect all candidate output links with this minimum weight
for (int link = 0; link < m_routing_table.size(); link++) {
if (msg_destination.intersectionIsNotEmpty(m_routing_table[link])) {
if (m_weight_table[link] == min_weight) {
num_candidates++;
output_link_candidates.push_back(link);
}
}
}
if (output_link_candidates.size() == 0) {
fatal("Fatal Error:: No Route exists from this Router.");
exit(0);
}
// Randomly select any candidate output link
int candidate = 0;
if (!(m_router->get_net_ptr())->isVNetOrdered(vnet))
candidate = rand() % num_candidates;
output_link = output_link_candidates.at(candidate);
return output_link;
}
void
RoutingUnit::addInDirection(PortDirection inport_dirn, int inport_idx)
{
m_inports_dirn2idx[inport_dirn] = inport_idx;
m_inports_idx2dirn[inport_idx] = inport_dirn;
}
void
RoutingUnit::addOutDirection(PortDirection outport_dirn, int outport_idx)
{
m_outports_dirn2idx[outport_dirn] = outport_idx;
m_outports_idx2dirn[outport_idx] = outport_dirn;
}
// outportCompute() is called by the InputUnit
// It calls the routing table by default.
// A template for adaptive topology-specific routing algorithm
// implementations using port directions rather than a static routing
// table is provided here.
int
RoutingUnit::outportCompute(RouteInfo route, int inport,
PortDirection inport_dirn)
{
int outport = -1;
if (route.dest_router == m_router->get_id()) {
// Multiple NIs may be connected to this router,
// all with output port direction = "Local"
// Get exact outport id from table
outport = lookupRoutingTable(route.vnet, route.net_dest);
return outport;
}
// Routing Algorithm set in GarnetNetwork.py
// Can be over-ridden from command line using --routing-algorithm = 1
RoutingAlgorithm routing_algorithm =
(RoutingAlgorithm) m_router->get_net_ptr()->getRoutingAlgorithm();
switch (routing_algorithm) {
case TABLE_: outport =
lookupRoutingTable(route.vnet, route.net_dest); break;
case XY_: outport =
outportComputeXY(route, inport, inport_dirn); break;
// any custom algorithm
case CUSTOM_: outport =
outportComputeCustom(route, inport, inport_dirn); break;
default: outport =
lookupRoutingTable(route.vnet, route.net_dest); break;
}
assert(outport != -1);
return outport;
}
// XY routing implemented using port directions
// Only for reference purpose in a Mesh
// By default Garnet uses the routing table
int
RoutingUnit::outportComputeXY(RouteInfo route,
int inport,
PortDirection inport_dirn)
{
PortDirection outport_dirn = "Unknown";
int M5_VAR_USED num_rows = m_router->get_net_ptr()->getNumRows();
int num_cols = m_router->get_net_ptr()->getNumCols();
assert(num_rows > 0 && num_cols > 0);
int my_id = m_router->get_id();
int my_x = my_id % num_cols;
int my_y = my_id / num_cols;
int dest_id = route.dest_router;
int dest_x = dest_id % num_cols;
int dest_y = dest_id / num_cols;
int x_hops = abs(dest_x - my_x);
int y_hops = abs(dest_y - my_y);
bool x_dirn = (dest_x >= my_x);
bool y_dirn = (dest_y >= my_y);
// already checked that in outportCompute() function
assert(!(x_hops == 0 && y_hops == 0));
if (x_hops > 0) {
if (x_dirn) {
assert(inport_dirn == "Local" || inport_dirn == "West");
outport_dirn = "East";
} else {
assert(inport_dirn == "Local" || inport_dirn == "East");
outport_dirn = "West";
}
} else if (y_hops > 0) {
if (y_dirn) {
// "Local" or "South" or "West" or "East"
assert(inport_dirn != "North");
outport_dirn = "North";
} else {
// "Local" or "North" or "West" or "East"
assert(inport_dirn != "South");
outport_dirn = "South";
}
} else {
// x_hops == 0 and y_hops == 0
// this is not possible
// already checked that in outportCompute() function
panic("x_hops == y_hops == 0");
}
return m_outports_dirn2idx[outport_dirn];
}
// Template for implementing custom routing algorithm
// using port directions. (Example adaptive)
int
RoutingUnit::outportComputeCustom(RouteInfo route,
int inport,
PortDirection inport_dirn)
{
panic("%s placeholder executed", __FUNCTION__);
}
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