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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())