configs/example/memtest.py - public/gem5 - Git at Google

 # Copyright (c) 2015, 2018 ARM Limited
 # All rights reserved.
 #
 # The license below extends only to copyright in the software and shall
 # not be construed as granting a license to any other intellectual
 # property including but not limited to intellectual property relating
 # to a hardware implementation of the functionality of the software
 # licensed hereunder.  You may use the software subject to the license
 # terms below provided that you ensure that this notice is replicated
 # unmodified and in its entirety in all distributions of the software,
 # modified or unmodified, in source code or in binary form.
 #
 # Copyright (c) 2006-2007 The Regents of The University of Michigan
 # 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.

 import argparse
 import random
 import sys

 import m5
 from m5.objects import *

 # This example script stress tests the memory system by creating false
 # sharing in a tree topology. At the bottom of the tree is a shared
 # memory, and then at each level a number of testers are attached,
 # along with a number of caches that them selves fan out to subtrees
 # of testers and caches. Thus, it is possible to create a system with
 # arbitrarily deep cache hierarchies, sharing or no sharing of caches,
 # and testers not only at the L1s, but also at the L2s, L3s etc.

 parser = argparse.ArgumentParser(
     formatter_class=argparse.ArgumentDefaultsHelpFormatter
 )

 parser.add_argument(
     "-a", "--atomic", action="store_true", help="Use atomic (non-timing) mode"
 )
 parser.add_argument(
     "-b", "--blocking", action="store_true", help="Use blocking caches"
 )
 parser.add_argument(
     "-l", "--maxloads", metavar="N", default=0, help="Stop after N loads"
 )
 parser.add_argument(
     "-m",
     "--maxtick",
     type=int,
     default=m5.MaxTick,
     metavar="T",
     help="Stop after T ticks",
 )

 # The tree specification consists of two colon-separated lists of one
 # or more integers, one for the caches, and one for the testers. The
 # first integer is the number of caches/testers closest to main
 # memory. Each cache then fans out to a subtree. The last integer in
 # the list is the number of caches/testers associated with the
 # uppermost level of memory. The other integers (if any) specify the
 # number of caches/testers connected at each level of the crossbar
 # hierarchy. The tester string should have one element more than the
 # cache string as there should always be testers attached to the
 # uppermost caches.

 parser.add_argument(
     "-c",
     "--caches",
     type=str,
     default="2:2:1",
     help="Colon-separated cache hierarchy specification, "
     "see script comments for details ",
 )
 parser.add_argument(
     "--noncoherent-cache",
     action="store_true",
     help="Adds a non-coherent, last-level cache",
 )
 parser.add_argument(
     "-t",
     "--testers",
     type=str,
     default="1:1:0:2",
     help="Colon-separated tester hierarchy specification, "
     "see script comments for details ",
 )
 parser.add_argument(
     "-f",
     "--functional",
     type=int,
     default=10,
     metavar="PCT",
     help="Target percentage of functional accesses ",
 )
 parser.add_argument(
     "-u",
     "--uncacheable",
     type=int,
     default=10,
     metavar="PCT",
     help="Target percentage of uncacheable accesses ",
 )
 parser.add_argument(
     "-r",
     "--random",
     action="store_true",
     help="Generate a random tree topology",
 )
 parser.add_argument(
     "--progress",
     type=int,
     default=100000,
     metavar="NLOADS",
     help="Progress message interval ",
 )
 parser.add_argument(
     "--sys-clock",
     action="store",
     type=str,
     default="1GHz",
     help="""Top-level clock for blocks running at system
                   speed""",
 )

 args = parser.parse_args()

 # Get the total number of testers
 def numtesters(cachespec, testerspec):
     # Determine the tester multiplier for each level as the
     # elements are per subsystem and it fans out
     multiplier = [1]
     for c in cachespec:
         multiplier.append(multiplier[-1] * c)

     total = 0
     for t, m in zip(testerspec, multiplier):
         total += t * m

     return total


 block_size = 64

 # Start by parsing the command line args and do some basic sanity
 # checking
 if args.random:
     # Generate a tree with a valid number of testers
     while True:
         tree_depth = random.randint(1, 4)
         cachespec = [random.randint(1, 3) for i in range(tree_depth)]
         testerspec = [random.randint(1, 3) for i in range(tree_depth + 1)]
         if numtesters(cachespec, testerspec) < block_size:
             break

     print(
         "Generated random tree -c",
         ":".join(map(str, cachespec)),
         "-t",
         ":".join(map(str, testerspec)),
     )
 else:
     try:
         cachespec = [int(x) for x in args.caches.split(":")]
         testerspec = [int(x) for x in args.testers.split(":")]
     except:
         print("Error: Unable to parse caches or testers option")
         sys.exit(1)

     if len(cachespec) < 1:
         print("Error: Must have at least one level of caches")
         sys.exit(1)

     if len(cachespec) != len(testerspec) - 1:
         print("Error: Testers must have one element more than caches")
         sys.exit(1)

     if testerspec[-1] == 0:
         print("Error: Must have testers at the uppermost level")
         sys.exit(1)

     for t in testerspec:
         if t < 0:
             print("Error: Cannot have a negative number of testers")
             sys.exit(1)

     for c in cachespec:
         if c < 1:
             print("Error: Must have 1 or more caches at each level")
             sys.exit(1)

     if numtesters(cachespec, testerspec) > block_size:
         print(
             f"Error: Limited to {block_size} testers because of false sharing"
         )
         sys.exit(1)

 # Define a prototype L1 cache that we scale for all successive levels
 proto_l1 = Cache(
     size="32kB",
     assoc=4,
     tag_latency=1,
     data_latency=1,
     response_latency=1,
     tgts_per_mshr=8,
     clusivity="mostly_incl",
     writeback_clean=True,
 )

 if args.blocking:
     proto_l1.mshrs = 1
 else:
     proto_l1.mshrs = 4

 cache_proto = [proto_l1]

 # Now add additional cache levels (if any) by scaling L1 params, the
 # first element is Ln, and the last element L1
 for scale in cachespec[:-1]:
     # Clone previous level and update params
     prev = cache_proto[0]
     next = prev()
     next.size = prev.size * scale
     next.tag_latency = prev.tag_latency * 10
     next.data_latency = prev.data_latency * 10
     next.response_latency = prev.response_latency * 10
     next.assoc = prev.assoc * scale
     next.mshrs = prev.mshrs * scale

     # Swap the inclusivity/exclusivity at each level. L2 is mostly
     # exclusive with respect to L1, L3 mostly inclusive, L4 mostly
     # exclusive etc.
     next.writeback_clean = not prev.writeback_clean
     if prev.clusivity.value == "mostly_incl":
         next.clusivity = "mostly_excl"
     else:
         next.clusivity = "mostly_incl"

     cache_proto.insert(0, next)

 # Make a prototype for the tester to be used throughout
 proto_tester = MemTest(
     max_loads=args.maxloads,
     percent_functional=args.functional,
     percent_uncacheable=args.uncacheable,
     progress_interval=args.progress,
 )

 # Set up the system along with a simple memory and reference memory
 system = System(physmem=SimpleMemory(), cache_line_size=block_size)

 system.voltage_domain = VoltageDomain(voltage="1V")

 system.clk_domain = SrcClockDomain(
     clock=args.sys_clock, voltage_domain=system.voltage_domain
 )

 # For each level, track the next subsys index to use
 next_subsys_index = [0] * (len(cachespec) + 1)

 # Recursive function to create a sub-tree of the cache and tester
 # hierarchy
 def make_cache_level(ncaches, prototypes, level, next_cache):
     global next_subsys_index, proto_l1, testerspec, proto_tester

     index = next_subsys_index[level]
     next_subsys_index[level] += 1

     # Create a subsystem to contain the crossbar and caches, and
     # any testers
     subsys = SubSystem()
     setattr(system, "l%dsubsys%d" % (level, index), subsys)

     # The levels are indexing backwards through the list
     ntesters = testerspec[len(cachespec) - level]

     # Scale the progress threshold as testers higher up in the tree
     # (smaller level) get a smaller portion of the overall bandwidth,
     # and also make the interval of packet injection longer for the
     # testers closer to the memory (larger level) to prevent them
     # hogging all the bandwidth
     limit = (len(cachespec) - level + 1) * 100000000
     testers = [
         proto_tester(interval=10 * (level * level + 1), progress_check=limit)
         for i in range(ntesters)
     ]
     if ntesters:
         subsys.tester = testers

     if level != 0:
         # Create a crossbar and add it to the subsystem, note that
         # we do this even with a single element on this level
         xbar = L2XBar()
         subsys.xbar = xbar
         if next_cache:
             xbar.mem_side_ports = next_cache.cpu_side

         # Create and connect the caches, both the ones fanning out
         # to create the tree, and the ones used to connect testers
         # on this level
         tree_caches = [prototypes[0]() for i in range(ncaches[0])]
         tester_caches = [proto_l1() for i in range(ntesters)]

         subsys.cache = tester_caches + tree_caches
         for cache in tree_caches:
             cache.mem_side = xbar.cpu_side_ports
             make_cache_level(ncaches[1:], prototypes[1:], level - 1, cache)
         for tester, cache in zip(testers, tester_caches):
             tester.port = cache.cpu_side
             cache.mem_side = xbar.cpu_side_ports
     else:
         if not next_cache:
             print("Error: No next-level cache at top level")
             sys.exit(1)

         if ntesters > 1:
             # Create a crossbar and add it to the subsystem
             xbar = L2XBar()
             subsys.xbar = xbar
             xbar.mem_side_ports = next_cache.cpu_side
             for tester in testers:
                 tester.port = xbar.cpu_side_ports
         else:
             # Single tester
             testers[0].port = next_cache.cpu_side


 # Top level call to create the cache hierarchy, bottom up
 make_cache_level(cachespec, cache_proto, len(cachespec), None)

 # Connect the lowest level crossbar to the last-level cache and memory
 # controller
 last_subsys = getattr(system, f"l{len(cachespec)}subsys0")
 last_subsys.xbar.point_of_coherency = True
 if args.noncoherent_cache:
     system.llc = NoncoherentCache(
         size="16MB",
         assoc=16,
         tag_latency=10,
         data_latency=10,
         sequential_access=True,
         response_latency=20,
         tgts_per_mshr=8,
         mshrs=64,
     )
     last_subsys.xbar.mem_side_ports = system.llc.cpu_side
     system.llc.mem_side = system.physmem.port
 else:
     last_subsys.xbar.mem_side_ports = system.physmem.port

 root = Root(full_system=False, system=system)
 if args.atomic:
     root.system.mem_mode = "atomic"
 else:
     root.system.mem_mode = "timing"

 # The system port is never used in the tester so merely connect it
 # to avoid problems
 root.system.system_port = last_subsys.xbar.cpu_side_ports

 # Instantiate configuration
 m5.instantiate()

 # Simulate until program terminates
 exit_event = m5.simulate(args.maxtick)

 print("Exiting @ tick", m5.curTick(), "because", exit_event.getCause())
	# Copyright (c) 2015, 2018 ARM Limited
	# All rights reserved.
	#
	# The license below extends only to copyright in the software and shall
	# not be construed as granting a license to any other intellectual
	# property including but not limited to intellectual property relating
	# to a hardware implementation of the functionality of the software
	# licensed hereunder. You may use the software subject to the license
	# terms below provided that you ensure that this notice is replicated
	# unmodified and in its entirety in all distributions of the software,
	# modified or unmodified, in source code or in binary form.
	#
	# Copyright (c) 2006-2007 The Regents of The University of Michigan
	# 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.

	import argparse
	import random
	import sys

	import m5
	from m5.objects import *

	# This example script stress tests the memory system by creating false
	# sharing in a tree topology. At the bottom of the tree is a shared
	# memory, and then at each level a number of testers are attached,
	# along with a number of caches that them selves fan out to subtrees
	# of testers and caches. Thus, it is possible to create a system with
	# arbitrarily deep cache hierarchies, sharing or no sharing of caches,
	# and testers not only at the L1s, but also at the L2s, L3s etc.

	parser = argparse.ArgumentParser(
	formatter_class=argparse.ArgumentDefaultsHelpFormatter
	)

	parser.add_argument(
	"-a", "--atomic", action="store_true", help="Use atomic (non-timing) mode"
	)
	parser.add_argument(
	"-b", "--blocking", action="store_true", help="Use blocking caches"
	)
	parser.add_argument(
	"-l", "--maxloads", metavar="N", default=0, help="Stop after N loads"
	)
	parser.add_argument(
	"-m",
	"--maxtick",
	type=int,
	default=m5.MaxTick,
	metavar="T",
	help="Stop after T ticks",
	)

	# The tree specification consists of two colon-separated lists of one
	# or more integers, one for the caches, and one for the testers. The
	# first integer is the number of caches/testers closest to main
	# memory. Each cache then fans out to a subtree. The last integer in
	# the list is the number of caches/testers associated with the
	# uppermost level of memory. The other integers (if any) specify the
	# number of caches/testers connected at each level of the crossbar
	# hierarchy. The tester string should have one element more than the
	# cache string as there should always be testers attached to the
	# uppermost caches.

	parser.add_argument(
	"-c",
	"--caches",
	type=str,
	default="2:2:1",
	help="Colon-separated cache hierarchy specification, "
	"see script comments for details ",
	)
	parser.add_argument(
	"--noncoherent-cache",
	action="store_true",
	help="Adds a non-coherent, last-level cache",
	)
	parser.add_argument(
	"-t",
	"--testers",
	type=str,
	default="1:1:0:2",
	help="Colon-separated tester hierarchy specification, "
	"see script comments for details ",
	)
	parser.add_argument(
	"-f",
	"--functional",
	type=int,
	default=10,
	metavar="PCT",
	help="Target percentage of functional accesses ",
	)
	parser.add_argument(
	"-u",
	"--uncacheable",
	type=int,
	default=10,
	metavar="PCT",
	help="Target percentage of uncacheable accesses ",
	)
	parser.add_argument(
	"-r",
	"--random",
	action="store_true",
	help="Generate a random tree topology",
	)
	parser.add_argument(
	"--progress",
	type=int,
	default=100000,
	metavar="NLOADS",
	help="Progress message interval ",
	)
	parser.add_argument(
	"--sys-clock",
	action="store",
	type=str,
	default="1GHz",
	help="""Top-level clock for blocks running at system
	speed""",
	)

	args = parser.parse_args()

	# Get the total number of testers
	def numtesters(cachespec, testerspec):
	# Determine the tester multiplier for each level as the
	# elements are per subsystem and it fans out
	multiplier = [1]
	for c in cachespec:
	multiplier.append(multiplier[-1] * c)

	total = 0
	for t, m in zip(testerspec, multiplier):
	total += t * m

	return total


	block_size = 64

	# Start by parsing the command line args and do some basic sanity
	# checking
	if args.random:
	# Generate a tree with a valid number of testers
	while True:
	tree_depth = random.randint(1, 4)
	cachespec = [random.randint(1, 3) for i in range(tree_depth)]
	testerspec = [random.randint(1, 3) for i in range(tree_depth + 1)]
	if numtesters(cachespec, testerspec) < block_size:
	break

	print(
	"Generated random tree -c",
	":".join(map(str, cachespec)),
	"-t",
	":".join(map(str, testerspec)),
	)
	else:
	try:
	cachespec = [int(x) for x in args.caches.split(":")]
	testerspec = [int(x) for x in args.testers.split(":")]
	except:
	print("Error: Unable to parse caches or testers option")
	sys.exit(1)

	if len(cachespec) < 1:
	print("Error: Must have at least one level of caches")
	sys.exit(1)

	if len(cachespec) != len(testerspec) - 1:
	print("Error: Testers must have one element more than caches")
	sys.exit(1)

	if testerspec[-1] == 0:
	print("Error: Must have testers at the uppermost level")
	sys.exit(1)

	for t in testerspec:
	if t < 0:
	print("Error: Cannot have a negative number of testers")
	sys.exit(1)

	for c in cachespec:
	if c < 1:
	print("Error: Must have 1 or more caches at each level")
	sys.exit(1)

	if numtesters(cachespec, testerspec) > block_size:
	print(
	f"Error: Limited to {block_size} testers because of false sharing"
	)
	sys.exit(1)

	# Define a prototype L1 cache that we scale for all successive levels
	proto_l1 = Cache(
	size="32kB",
	assoc=4,
	tag_latency=1,
	data_latency=1,
	response_latency=1,
	tgts_per_mshr=8,
	clusivity="mostly_incl",
	writeback_clean=True,
	)

	if args.blocking:
	proto_l1.mshrs = 1
	else:
	proto_l1.mshrs = 4

	cache_proto = [proto_l1]

	# Now add additional cache levels (if any) by scaling L1 params, the
	# first element is Ln, and the last element L1
	for scale in cachespec[:-1]:
	# Clone previous level and update params
	prev = cache_proto[0]
	next = prev()
	next.size = prev.size * scale
	next.tag_latency = prev.tag_latency * 10
	next.data_latency = prev.data_latency * 10
	next.response_latency = prev.response_latency * 10
	next.assoc = prev.assoc * scale
	next.mshrs = prev.mshrs * scale

	# Swap the inclusivity/exclusivity at each level. L2 is mostly
	# exclusive with respect to L1, L3 mostly inclusive, L4 mostly
	# exclusive etc.
	next.writeback_clean = not prev.writeback_clean
	if prev.clusivity.value == "mostly_incl":
	next.clusivity = "mostly_excl"
	else:
	next.clusivity = "mostly_incl"

	cache_proto.insert(0, next)

	# Make a prototype for the tester to be used throughout
	proto_tester = MemTest(
	max_loads=args.maxloads,
	percent_functional=args.functional,
	percent_uncacheable=args.uncacheable,
	progress_interval=args.progress,
	)

	# Set up the system along with a simple memory and reference memory
	system = System(physmem=SimpleMemory(), cache_line_size=block_size)

	system.voltage_domain = VoltageDomain(voltage="1V")

	system.clk_domain = SrcClockDomain(
	clock=args.sys_clock, voltage_domain=system.voltage_domain
	)

	# For each level, track the next subsys index to use
	next_subsys_index = [0] * (len(cachespec) + 1)

	# Recursive function to create a sub-tree of the cache and tester
	# hierarchy
	def make_cache_level(ncaches, prototypes, level, next_cache):
	global next_subsys_index, proto_l1, testerspec, proto_tester

	index = next_subsys_index[level]
	next_subsys_index[level] += 1

	# Create a subsystem to contain the crossbar and caches, and
	# any testers
	subsys = SubSystem()
	setattr(system, "l%dsubsys%d" % (level, index), subsys)

	# The levels are indexing backwards through the list
	ntesters = testerspec[len(cachespec) - level]

	# Scale the progress threshold as testers higher up in the tree
	# (smaller level) get a smaller portion of the overall bandwidth,
	# and also make the interval of packet injection longer for the
	# testers closer to the memory (larger level) to prevent them
	# hogging all the bandwidth
	limit = (len(cachespec) - level + 1) * 100000000
	testers = [
	proto_tester(interval=10 * (level * level + 1), progress_check=limit)
	for i in range(ntesters)
	]
	if ntesters:
	subsys.tester = testers

	if level != 0:
	# Create a crossbar and add it to the subsystem, note that
	# we do this even with a single element on this level
	xbar = L2XBar()
	subsys.xbar = xbar
	if next_cache:
	xbar.mem_side_ports = next_cache.cpu_side

	# Create and connect the caches, both the ones fanning out
	# to create the tree, and the ones used to connect testers
	# on this level
	tree_caches = [prototypes[0]() for i in range(ncaches[0])]
	tester_caches = [proto_l1() for i in range(ntesters)]

	subsys.cache = tester_caches + tree_caches
	for cache in tree_caches:
	cache.mem_side = xbar.cpu_side_ports
	make_cache_level(ncaches[1:], prototypes[1:], level - 1, cache)
	for tester, cache in zip(testers, tester_caches):
	tester.port = cache.cpu_side
	cache.mem_side = xbar.cpu_side_ports
	else:
	if not next_cache:
	print("Error: No next-level cache at top level")
	sys.exit(1)

	if ntesters > 1:
	# Create a crossbar and add it to the subsystem
	xbar = L2XBar()
	subsys.xbar = xbar
	xbar.mem_side_ports = next_cache.cpu_side
	for tester in testers:
	tester.port = xbar.cpu_side_ports
	else:
	# Single tester
	testers[0].port = next_cache.cpu_side


	# Top level call to create the cache hierarchy, bottom up
	make_cache_level(cachespec, cache_proto, len(cachespec), None)

	# Connect the lowest level crossbar to the last-level cache and memory
	# controller
	last_subsys = getattr(system, f"l{len(cachespec)}subsys0")
	last_subsys.xbar.point_of_coherency = True
	if args.noncoherent_cache:
	system.llc = NoncoherentCache(
	size="16MB",
	assoc=16,
	tag_latency=10,
	data_latency=10,
	sequential_access=True,
	response_latency=20,
	tgts_per_mshr=8,
	mshrs=64,
	)
	last_subsys.xbar.mem_side_ports = system.llc.cpu_side
	system.llc.mem_side = system.physmem.port
	else:
	last_subsys.xbar.mem_side_ports = system.physmem.port

	root = Root(full_system=False, system=system)
	if args.atomic:
	root.system.mem_mode = "atomic"
	else:
	root.system.mem_mode = "timing"

	# The system port is never used in the tester so merely connect it
	# to avoid problems
	root.system.system_port = last_subsys.xbar.cpu_side_ports

	# Instantiate configuration
	m5.instantiate()

	# Simulate until program terminates
	exit_event = m5.simulate(args.maxtick)

	print("Exiting @ tick", m5.curTick(), "because", exit_event.getCause())