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# Copyright (c) 2011 Advanced Micro Devices, Inc.
# 2011 Massachusetts 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: Brad Beckmann
# Tushar Krishna
from m5.params import *
from m5.objects import *
class Torus(Topology):
description='Torus'
# Makes a generic torus assuming an equal number of cache and directory cntrls
# Assuming a folded-torus on-chip layout (as shown on gem5 wiki).
# All links (including the wrap-around ones) are of equal length, double that
# of a mesh. Thus, each link is assigned a latency of 2 cycles.
def makeTopology(nodes, options, IntLink, ExtLink, Router):
num_routers = options.num_cpus
num_rows = options.mesh_rows
# There must be an evenly divisible number of cntrls to routers
# Also, obviously the number or rows must be <= the number of routers
cntrls_per_router, remainder = divmod(len(nodes), num_routers)
assert(num_rows <= num_routers)
num_columns = int(num_routers / num_rows)
assert(num_columns * num_rows == num_routers)
# Create the routers in the torus
routers = [Router(router_id=i) for i in range(num_routers)]
# link counter to set unique link ids
link_count = 0
# Add all but the remainder nodes to the list of nodes to be uniformly
# distributed across the network.
network_nodes = []
remainder_nodes = []
for node_index in xrange(len(nodes)):
if node_index < (len(nodes) - remainder):
network_nodes.append(nodes[node_index])
else:
remainder_nodes.append(nodes[node_index])
# Connect each node to the appropriate router
ext_links = []
for (i, n) in enumerate(network_nodes):
cntrl_level, router_id = divmod(i, num_routers)
assert(cntrl_level < cntrls_per_router)
ext_links.append(ExtLink(link_id=link_count, ext_node=n,
int_node=routers[router_id]))
link_count += 1
# Connect the remainding nodes to router 0. These should only be
# DMA nodes.
for (i, node) in enumerate(remainder_nodes):
assert(node.type == 'DMA_Controller')
assert(i < remainder)
ext_links.append(ExtLink(link_id=link_count, ext_node=node,
int_node=routers[0]))
link_count += 1
# Create the torus links. First row (east-west) links then column
# (north-south) links
# column links are given higher weights to implement XY routing
int_links = []
for row in xrange(num_rows):
for col in xrange(num_columns):
west_id = col + (row * num_columns)
if (col + 1 < num_columns):
east_id = (col + 1) + (row * num_columns)
else:
east_id = (row * num_columns)
int_links.append(IntLink(link_id=link_count,
node_a=routers[east_id],
node_b=routers[west_id],
latency=2,
weight=1))
link_count += 1
for col in xrange(num_columns):
for row in xrange(num_rows):
north_id = col + (row * num_columns)
if (row + 1 < num_rows):
south_id = col + ((row + 1) * num_columns)
else:
south_id = col
int_links.append(IntLink(link_id=link_count,
node_a=routers[north_id],
node_b=routers[south_id],
latency=2,
weight=2))
link_count += 1
return Torus(ext_links=ext_links,
int_links=int_links,
routers=routers)
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