HMC.py revision 11292
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13# Copyright (c) 2015 The University of Bologna
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38#
39# Authors: Erfan Azarkhish
40
41# A Simplified model of a complete HMC device. Based on:
42#  [1] http://www.hybridmemorycube.org/specification-download/
43#  [2] High performance AXI-4.0 based interconnect for extensible smart memory
44#      cubes(E. Azarkhish et. al)
45#  [3] Low-Power Hybrid Memory Cubes With Link Power Management and Two-Level
46#      Prefetching (J. Ahn et. al)
47#  [4] Memory-centric system interconnect design with Hybrid Memory Cubes
48#      (G. Kim et. al)
49#  [5] Near Data Processing, Are we there yet? (M. Gokhale)
50#      http://www.cs.utah.edu/wondp/gokhale.pdf
51#
52# This script builds a complete HMC device composed of vault controllers,
53# serial links, the main internal crossbar, and an external hmc controller.
54#
55# - VAULT CONTROLLERS:
56#   Instances of the HMC_2500_x32 class with their functionality specified in
57#   dram_ctrl.cc
58#
59# - THE MAIN XBAR:
60#   This component is simply an instance of the NoncoherentXBar class, and its
61#   parameters are tuned to [2].
62#
63# - SERIAL LINKS:
64#   SerialLink is a simple variation of the Bridge class, with the ability to
65#   account for the latency of packet serialization. We assume that the
66#   serializer component at the transmitter side does not need to receive the
67#   whole packet to start the serialization. But the deserializer waits for
68#   the complete packet to check its integrity first.
69#   * Bandwidth of the serial links is not modeled in the SerialLink component
70#     itself. Instead bandwidth/port of the HMCController has been adjusted to
71#     reflect the bandwidth delivered by 1 serial link.
72#
73# - HMC CONTROLLER:
74#   Contains a large buffer (modeled with Bridge) to hide the access latency
75#   of the memory cube. Plus it simply forwards the packets to the serial
76#   links in a round-robin fashion to balance load among them.
77#   * It is inferred from the standard [1] and the literature [3] that serial
78#     links share the same address range and packets can travel over any of
79#     them so a load distribution mechanism is required among them.
80
81import optparse
82
83import m5
84from m5.objects import *
85
86# A single Hybrid Memory Cube (HMC)
87class HMCSystem(SubSystem):
88    #*****************************CROSSBAR PARAMETERS*************************
89    # Flit size of the main interconnect [1]
90    xbar_width = Param.Unsigned(32, "Data width of the main XBar (Bytes)")
91
92    # Clock frequency of the main interconnect [1]
93    # This crossbar, is placed on the logic-based of the HMC and it has its
94    # own voltage and clock domains, different from the DRAM dies or from the
95    # host.
96    xbar_frequency = Param.Frequency('1GHz', "Clock Frequency of the main "
97        "XBar")
98
99    # Arbitration latency of the HMC XBar [1]
100    xbar_frontend_latency = Param.Cycles(1, "Arbitration latency of the XBar")
101
102    # Latency to forward a packet via the interconnect [1](two levels of FIFOs
103    # at the input and output of the inteconnect)
104    xbar_forward_latency = Param.Cycles(2, "Forward latency of the XBar")
105
106    # Latency to forward a response via the interconnect [1](two levels of
107    # FIFOs at the input and output of the inteconnect)
108    xbar_response_latency = Param.Cycles(2, "Response latency of the XBar")
109
110    #*****************************SERIAL LINK PARAMETERS**********************
111    # Number of serial links [1]
112    num_serial_links = Param.Unsigned(4, "Number of serial links")
113
114    # Number of packets (not flits) to store at the request side of the serial
115    #  link. This number should be adjusted to achive required bandwidth
116    link_buffer_size_req = Param.Unsigned(16, "Number of packets to buffer "
117        "at the request side of the serial link")
118
119    # Number of packets (not flits) to store at the response side of the serial
120    #  link. This number should be adjusted to achive required bandwidth
121    link_buffer_size_rsp = Param.Unsigned(16, "Number of packets to buffer "
122        "at the response side of the serial link")
123
124    # Latency of the serial link composed by SER/DES latency (1.6ns [4]) plus
125    # the PCB trace latency (3ns Estimated based on [5])
126    link_latency = Param.Latency('4.6ns', "Latency of the serial links")
127
128    # Header overhead of the serial links: Header size is 128bits in HMC [1],
129    #  and we have 16 lanes, so the overhead is 8 cycles
130    link_overhead = Param.Cycles(8, "The number of cycles required to"
131        " transmit the packet header over the serial link")
132
133    # Clock frequency of the serial links [1]
134    link_frequency = Param.Frequency('10GHz', "Clock Frequency of the serial"
135        "links")
136
137    # Number of parallel lanes in each serial link [1]
138    num_lanes_per_link =  Param.Unsigned(16, "Number of lanes per each link")
139
140    # Number of serial links [1]
141    num_serial_links =  Param.Unsigned(4, "Number of serial links")
142
143    #*****************************HMC CONTROLLER PARAMETERS*******************
144    # Number of packets (not flits) to store at the HMC controller. This
145    # number should be high enough to be able to hide the high latency of HMC
146    ctrl_buffer_size_req = Param.Unsigned(256, "Number of packets to buffer "
147        "at the HMC controller (request side)")
148
149    # Number of packets (not flits) to store at the response side of the HMC
150    #  controller.
151    ctrl_buffer_size_rsp = Param.Unsigned(256, "Number of packets to buffer "
152        "at the HMC controller (response side)")
153
154    # Latency of the HMC controller to process the packets
155    # (ClockDomain = Host clock domain)
156    ctrl_latency = Param.Cycles(4, "The number of cycles required for the "
157        " controller to process the packet")
158
159    # Wiring latency from the SoC crossbar to the HMC controller
160    ctrl_static_latency = Param.Latency('500ps', "Static latency of the HMC"
161        "controller")
162
163    #*****************************PERFORMANCE MONITORING**********************
164    # The main monitor behind the HMC Controller
165    enable_global_monitor = Param.Bool(True, "The main monitor behind the "
166        "HMC Controller")
167
168    # The link performance monitors
169    enable_link_monitor = Param.Bool(True, "The link monitors")
170
171# Create an HMC device and attach it to the current system
172def config_hmc(options, system):
173
174    system.hmc = HMCSystem()
175
176    system.buffer = Bridge(ranges=system.mem_ranges,
177                           req_size=system.hmc.ctrl_buffer_size_req,
178                           resp_size=system.hmc.ctrl_buffer_size_rsp,
179                           delay=system.hmc.ctrl_static_latency)
180    try:
181        system.hmc.enable_global_monitor = options.enable_global_monitor
182    except:
183        pass;
184
185    try:
186        system.hmc.enable_link_monitor = options.enable_link_monitor
187    except:
188        pass;
189
190    system.membus.master = system.buffer.slave
191
192    # The HMC controller (Clock domain is the same as the host)
193    system.hmccontroller = HMCController(width=(system.hmc.num_lanes_per_link.
194        value * system.hmc.num_serial_links/8),
195        frontend_latency=system.hmc.ctrl_latency,
196        forward_latency=system.hmc.link_overhead,
197        response_latency=system.hmc.link_overhead)
198
199    system.hmccontroller.clk_domain = SrcClockDomain(clock=system.hmc.
200        link_frequency, voltage_domain = VoltageDomain(voltage = '1V'))
201
202    # Serial Links
203    system.hmc.seriallink =[ SerialLink(ranges = system.mem_ranges,
204        req_size=system.hmc.link_buffer_size_req,
205        resp_size=system.hmc.link_buffer_size_rsp,
206        num_lanes=system.hmc.num_lanes_per_link,
207        delay=system.hmc.link_latency)
208        for i in xrange(system.hmc.num_serial_links)]
209
210    if system.hmc.enable_link_monitor:
211        system.hmc.lmonitor = [ CommMonitor()
212        for i in xrange(system.hmc.num_serial_links)]
213
214    # The HMC Crossbar located in its logic-base (LoB)
215    system.hmc.xbar = NoncoherentXBar(width = system.hmc.xbar_width,
216        frontend_latency=system.hmc.xbar_frontend_latency,
217        forward_latency=system.hmc.xbar_forward_latency,
218        response_latency=system.hmc.xbar_response_latency )
219    system.hmc.xbar.clk_domain = SrcClockDomain(clock =
220        system.hmc.xbar_frequency, voltage_domain =
221        VoltageDomain(voltage = '1V'))
222
223    if system.hmc.enable_global_monitor:
224        system.gmonitor = CommMonitor()
225        system.buffer.master = system.gmonitor.slave
226        system.gmonitor.master = system.hmccontroller.slave
227    else:
228        system.hmccontroller.slave = system.buffer.master
229
230    for i in xrange(system.hmc.num_serial_links):
231        system.hmccontroller.master = system.hmc.seriallink[i].slave
232        system.hmc.seriallink[i].clk_domain = system.hmccontroller.clk_domain;
233        if system.hmc.enable_link_monitor:
234            system.hmc.seriallink[i].master = system.hmc.lmonitor[i].slave
235            system.hmc.lmonitor[i].master = system.hmc.xbar.slave
236        else:
237            system.hmc.seriallink[i].master = system.hmc.xbar.slave
238