gem5_example


Hardware simulators - gem5 target support

The gem5 simulator is a modular platform for computer-system architecture research, encompassing system-level architecture as well as processor microarchitecture.

Before creating the gem5 target, the inputs needed by gem5 should have been created (eg gem5 binary, kernel suitable for gem5, disk image, device tree blob, etc). For more information, see GEM5 - Main Page.

Environment setup


In [1]:
from conf import LisaLogging
LisaLogging.setup()


2017-07-19 09:55:37,733 INFO    : root         : Using LISA logging configuration:
2017-07-19 09:55:37,733 INFO    : root         :   /home/vagrant/lisa/logging.conf

In [2]:
# One initial cell for imports
import json
import logging
import os

from env import TestEnv

# Suport for FTrace events parsing and visualization
import trappy
from trappy.ftrace import FTrace
from trace import Trace

# Support for plotting
# Generate plots inline
%matplotlib inline
import numpy
import pandas as pd
import matplotlib.pyplot as plt


2017-07-19 09:55:39,016 WARNING : EnergyModel  : Unusual max capacity (1023), overriding capacity_scale

Target configuration

The definitions below need to be changed to the paths pointing to the gem5 binaries on your development machine. M5_PATH needs to be set in your environment

  • platform - the currently supported platforms are:

    • linux - accessed via SSH connection
  • board - the currently supported boards are:

    • gem5 - target is a gem5 simulator
  • host - target IP or MAC address of the platform hosting the simulator

  • gem5 - the settings for the simulation are:

    • system

      • platform

        • description - python description of the platform to simulate
        • args - arguments to be given to the python script (./gem5.fast model.py --help)
      • kernel - kernel image to run on the simulated platform

      • dtb - dtb of the platform to simulate
      • disk - disk image to run on the platform
    • simulator
      • bin - path to the gem5 simulator binary
      • args - arguments to be given to the gem5 binary (./gem5.fast --help)
  • modules - devlib modules to be enabled

  • exclude_modules - devlib modules to be disabled

  • tools - binary tools (available under ./tools/$ARCH/) to install by default

  • ping_time - wait time before trying to access the target after reboot

  • reboot_time - maximum time to wait after rebooting the target

  • features - list of test environment features to enable

    • no-kernel - do not deploy kernel/dtb images
    • no-reboot - do not force reboot the target at each configuration change
    • debug - enable debugging messages
  • ftrace - ftrace configuration

    • events
    • functions
    • buffsize
  • results_dir - location of results of the experiments


In [3]:
# Root path of the gem5 workspace
base = "/home/vagrant/gem5/"

conf = {
    # Only 'linux' is supported by gem5 for now
    # 'android' is a WIP
    "platform"    : 'linux',
    
    # Preload settings for a specific target
    "board"       : 'gem5',

    # Host that will run the gem5 instance
    "host"        : "workstation-lin",
    
    "gem5" : {
        # System to simulate
        "system" : {
            # Platform description
            "platform" : {
                # Gem5 platform description
                # LISA will also look for an optional gem5<platform> board file
                # located in the same directory as the description file.
                "description" : os.path.join(base, "juno.py"),
                "args" : [
                    "--atomic",
                    # Resume simulation from a previous checkpoint
                    # Checkpoint must be taken before Virtio folders are mounted
                    # "--checkpoint-indir " + os.path.join(base, "Juno/atomic/",
                    #                                      "checkpoints"),
                    # "--checkpoint-resume 1",
                ]
            },
            # Kernel compiled for gem5 with Virtio flags
            "kernel"   : os.path.join(base, "platform_juno/", "vmlinux"),
            # DTB of the system to simulate
            "dtb"      : os.path.join(base, "platform_juno/", "armv8_juno_r2.dtb"),
            # Disk of the distrib to run
            "disk"     : os.path.join(base, "binaries/", "aarch64-ubuntu-trusty-headless.img")
        },
        # gem5 settings
        "simulator" : {
            # Path to gem5 binary
            "bin"     : os.path.join(base, "gem5/build/ARM/gem5.fast"),
            # Args to be given to the binary
            "args" : [
                # Zilch
            ],
        }
    },

    # FTrace events to collect for all the tests configuration which have
    # the "ftrace" flag enabled
    "ftrace"  : {
         "events" : [
            "sched_switch",
            "sched_wakeup",
            "sched_overutilized",
            "sched_load_avg_cpu",
            "sched_load_avg_task",
            "sched_load_waking_task",
            "cpu_capacity",
            "cpu_frequency",
            "cpu_idle",
            "sched_energy_diff"
        ],
        "buffsize" : 100 * 1024,
    },
    
    "modules" : ["cpufreq", "bl", "gem5stats"],

    # Tools required by the experiments
    "tools"   : ['trace-cmd', 'sysbench'],
    
    # Output directory on host
    "results_dir" : "gem5_res"
}

In [4]:
# Create the hardware target. Patience is required :
# ~40 minutes to resume from a checkpoint (detailed)
# ~5 minutes to resume from a checkpoint (atomic)
# ~3 hours to start from scratch (detailed)
# ~15 minutes to start from scratch (atomic)
te = TestEnv(conf)
target = te.target


2017-07-19 09:55:44,645 INFO    : TestEnv      : Using base path: /home/vagrant/lisa
2017-07-19 09:55:44,646 INFO    : TestEnv      : Loading custom (inline) target configuration
2017-07-19 09:55:44,647 WARNING : TestEnv      : Wipe previous contents of the results folder:
2017-07-19 09:55:44,648 WARNING : TestEnv      :    /home/vagrant/lisa/results/gem5_res
2017-07-19 09:55:44,653 INFO    : TestEnv      : Loading board:
2017-07-19 09:55:44,654 INFO    : TestEnv      :    /home/vagrant/lisa/libs/utils/platforms/gem5juno.json
2017-07-19 09:55:44,655 INFO    : gem5         : Creating temporary directory for interaction  with gem5 via virtIO: /tmp/wa_0
2017-07-19 09:55:44,655 INFO    : gem5         : Starting the gem5 simulator
2017-07-19 09:55:45,662 INFO    : TestEnv      : Devlib modules to load: ['bl', 'cpufreq', 'gem5stats']
2017-07-19 09:55:45,663 INFO    : TestEnv      : Connecting linux target:
2017-07-19 09:55:45,663 INFO    : TestEnv      :   username : root
2017-07-19 09:55:45,664 INFO    : TestEnv      :       host : workstation-lin
2017-07-19 09:55:45,664 INFO    : TestEnv      :   password : 
2017-07-19 09:55:45,665 INFO    : TestEnv      : Connection settings:
2017-07-19 09:55:45,665 INFO    : TestEnv      :    {'username': 'root', 'host': 'workstation-lin', 'password': ''}
2017-07-19 09:55:45,669 INFO    : gem5-connection : Connecting to the gem5 simulation on port 3456
2017-07-19 09:55:56,388 INFO    : gem5-connection : Connected! Waiting for prompt...
2017-07-19 09:55:56,389 INFO    : gem5-connection : Created lock file /tmp/workstation-lin_3456.LOCK to prevent reconnecting to same simulation
2017-07-19 09:55:56,390 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 09:57:06,511 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 09:58:16,632 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 09:59:26,725 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 10:00:36,846 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 10:01:46,957 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 10:02:57,054 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 10:04:07,150 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 10:05:17,253 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 10:06:27,361 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 10:07:37,435 INFO    : gem5-connection : Trying to log in to gem5 device
2017-07-19 10:08:06,874 INFO    : gem5-connection : Successfully logged in
2017-07-19 10:08:06,875 INFO    : gem5-connection : Setting unique prompt...
2017-07-19 10:08:07,387 INFO    : gem5-connection : Prompt found and replaced with a unique string
2017-07-19 10:08:07,772 INFO    : gem5-connection : Mounting VirtIO device in simulated system
2017-07-19 10:09:39,550 INFO    : TestEnv      : Initializing target workdir:
2017-07-19 10:09:39,550 INFO    : TestEnv      :    /home/root/devlib-target
2017-07-19 10:11:29,983 INFO    : TestEnv      : Attempting to read energy model from target
2017-07-19 10:11:29,984 ERROR   : TestEnv      : Couldn't read target energy model: Requires cpuidle devlib module. Please ensure "cpuidle" is listed in your target/test modules
2017-07-19 10:11:29,984 INFO    : TestEnv      : Topology:
2017-07-19 10:11:29,985 INFO    : TestEnv      :    [[0, 1, 2, 3], [4, 5]]
2017-07-19 10:11:36,961 INFO    : TestEnv      : Loading default EM:
2017-07-19 10:11:36,961 INFO    : TestEnv      :    /home/vagrant/lisa/libs/utils/platforms/gem5juno.json
2017-07-19 10:12:01,903 WARNING : LinuxTarget  : Event [sched_load_waking_task] not available for tracing
2017-07-19 10:12:01,905 INFO    : TestEnv      : Enabled tracepoints:
2017-07-19 10:12:01,905 INFO    : TestEnv      :    sched_switch
2017-07-19 10:12:01,906 INFO    : TestEnv      :    sched_wakeup
2017-07-19 10:12:01,906 INFO    : TestEnv      :    sched_overutilized
2017-07-19 10:12:01,906 INFO    : TestEnv      :    sched_load_avg_cpu
2017-07-19 10:12:01,907 INFO    : TestEnv      :    sched_load_avg_task
2017-07-19 10:12:01,907 INFO    : TestEnv      :    sched_load_waking_task
2017-07-19 10:12:01,907 INFO    : TestEnv      :    cpu_capacity
2017-07-19 10:12:01,908 INFO    : TestEnv      :    cpu_frequency
2017-07-19 10:12:01,908 INFO    : TestEnv      :    cpu_idle
2017-07-19 10:12:01,909 INFO    : TestEnv      :    sched_energy_diff
2017-07-19 10:12:01,909 INFO    : TestEnv      : Set results folder to:
2017-07-19 10:12:01,910 INFO    : TestEnv      :    /home/vagrant/lisa/results/gem5_res
2017-07-19 10:12:01,911 INFO    : TestEnv      : Experiment results available also in:
2017-07-19 10:12:01,912 INFO    : TestEnv      :    /home/vagrant/lisa/results_latest

Run workloads on gem5

This is an example of running a workload and extracting stats from the simulation using m5 commands. For more information about m5 commands, see http://gem5.org/M5ops


In [5]:
# This function is an example use of gem5's ROI functionality
def record_time(command):
    roi = 'time'
    target.gem5stats.book_roi(roi)
    
    target.gem5stats.roi_start(roi)
    target.execute(command)
    target.gem5stats.roi_end(roi)
    
    res = target.gem5stats.match(['host_seconds', 'sim_seconds'], [roi])
    
    target.gem5stats.free_roi(roi)
    
    return res

In [6]:
# Initialise command: [binary/script, arguments]
workload = 'sysbench'
args = '--test=cpu --max-time=1 run'

# Install binary if needed
path = target.install_if_needed("/home/vagrant/lisa/tools/arm64/" + workload)
command = path + " " + args

# FTrace the execution of this workload
te.ftrace.start()
res = record_time(command)
te.ftrace.stop()

print "{} -> {}s wall-clock execution time, {}s simulation-clock execution time".format(command,
        sum(map(float, res['host_seconds']['time'])),
        sum(map(float, res['sim_seconds']['time'])))


/home/root/devlib-target/bin/sysbench --test=cpu --max-time=1 run -> 349.49s wall-clock execution time, 1.052278s simulation-clock execution time

Trace analysis

For more information on this please check examples/trace_analysis/TraceAnalysis_TasksLatencies.ipynb.


In [7]:
# Load traces in memory (can take several minutes)
platform_file = os.path.join(te.res_dir, 'platform.json')
te.platform_dump(te.res_dir, platform_file)

with open(platform_file, 'r') as fh:
    platform = json.load(fh)

trace_file = os.path.join(te.res_dir, 'trace.dat')
te.ftrace.get_trace(trace_file)
trace = Trace(trace_file, conf['ftrace']['events'], platform, normalize_time=False)


2017-07-19 10:27:58,358 INFO    : Trace        : Platform clusters verified to be Frequency coherent

In [8]:
# Plot some stuff
trace.analysis.cpus.plotCPU()



In [9]:
# Simulations done
target.disconnect()


2017-07-19 10:28:54,619 INFO    : gem5-connection : Gracefully terminating the gem5 simulation.
2017-07-19 10:28:56,068 INFO    : gem5-connection : Removing the temporary directory