Gem5 part2

A Modular platform for computer-system architecture research

chsgcxy

• Ruby memory sub-system

• Power and thermal model

• GPU

Ruby implements a detailed simulation model for the memory subsystem

• Inclusive/exclusive cache hierarchies

• Various replacement policies

• Coherence protocol implementations

• Interconnection networks

• DMA and memory controllers

  

• Various sequencers

• NetWork

  • GarnetNetWork

  • SimpleNetWork

• Protocol

  • MI_example

  • MESI_Two_level

  • MOESI_CMP_directory

  • MOESI_CMP_token

  • MOESI_hammer

  • Garnet_standalone

  • MESI_Three_Level

  • CHI

    
    

    Interconnection network could be replaced with the external simulator TOPAZ.

    This simulator is ready to run within gem5 and adds a significant number of features over original ruby network simulator.

    It includes, new advanced router micro-architectures, new topologies, precision-performance adjustable router models, mechanisms to speed-up network simulation, etc

    ceunican/tpzsimul: Automatically exported from code.google.com/p/tpzsimul (github.com)

    
    

    Topology

    
    

    

    
    

    
    

    PROTOCOL

    scons build/ARM/gem5.debug PROTOCOL=CHI

    
    

    *CHI only support CustomMesh topology

    
    

    Run an example

    CHI

    
    

    

    ./build/ARM/gem5.debug configs/example/se.py

    --cpu-type=ArmO3CPU

    --caches --l2cache --mem-type=DDR4_2400_8x8

    --mem-size=2GB --l1d_size=64kB --l1i_size=32kB

    --l2_size=512kB -n 4 --ruby

    --topology=CustomMesh

    --chi-config=configs/example/noc_config/2x4.py

    -c tests/test-progs/threads/src/threads

    • MI_example

    • MESI_Two_level

    • MOESI_CMP_directory

    • MOESI_CMP_token

    • MOESI_hammer

    • Garnet_standalone

    • MESI_Three_Level

    • CHI

    Topology dot file

    
    

    2x4.py

    

    
    

    CHI 2x4 Connected by link

    
    

    

    src/python/m5/util/dot_writer_ruby.py

    Need to rebuild when change the file

    
    

    Garnet Router

    
    

    

    credit

    
    

• Gem5 power consumption model:

  gem5 itself cannot provide complete power information. Although the power consumption model of the memory part is relatively complete, it lacks a more accurate CPU power consumption model.

  
  

  • configs/example/arm/fs_power.py

  • support ARM DVFS

    
    

• Gem5 stat.txt + mcpat

  Although there are some third-party tools that can calculate detailed energy consumption information based on the output of gem5 simulator, such as mcpat, etc., studies have shown that the calculation results of these tools have a large error with the results obtained by hardware measuring instruments

  
  

  

  • ext/mcpat

gem5: ARM Power Modelling gem5: ARM DVFS Support

src/arch/amdgpu/

def connectGPU(system, args):

system.pc.south_bridge.gpu = AMDGPUDevice(pci_func=0, pci_dev=8, pci_bus=0)

system.pc.south_bridge.gpu.trace_file = args.gpu_mmio_trace system.pc.south_bridge.gpu.rom_binary = args.gpu_rom system.pc.south_bridge.gpu.checkpoint_before_mmios = \

args.checkpoint_before_mmios

class AMDGPUDevice : public PciDevice

Only support AMD GPU

define gpu instructions

AMD vega/gcn3

X86 CPU

Only se mode

PCIE

src/dev/amdgpu/

define gpu device

src/dev/gpu-compute/

gpu micro architecture

a Docker image that contains the proper software and libraries needed to run the GPU model in gem5 Reference: util/dockerfiles/gcn-gpu/README.md

QA

Thanks