Architetture dei Sistemi di Elaborazione@Politecnico di Torino: SIMULATING AN OoO RISC-V CPU WITH GEM5
This README provides an environment for simulating a program on a parametrizable RISC-V Out of Order (OoO) CPU and visualize the pipeline. You can see the flow in the Figure below.
First of all, you need to clone the repository with the following command, for SSH:
git clone [email protected]:cad-polito-it/ase_riscv_gem5_sim.git
For HTTPS:
git clone https://github.com/cad-polito-it/ase_riscv_gem5_sim.git
In order to simulate a benchmark, you need the following three tools:
- A Risc-V cross compiler
- An architectural simulator
- A pipeline visualizer
Installation guidelines are provided for each of the aforementioned tools. In case you are using LABINF PCs, you can skip the installation part (Be aware, tools' compilation is time consuming!).
An important file for the simulation flow is the setup_default
.
In this file you need to specify you installation paths for different tools.
For example:
export CC="/usr/bin/riscv64-linux-gnu-gcc-10"
export GEM5_INSTALLATION_PATH="/mnt/d/gem5_simulator/build/"
export GEM5_SRC="/mnt/d/gem5_simulator/gem5/"
The CC
is the cross compiler, and it is installed in /usr/bin
. Meanwhile the Architectural Simulator (Gem5) is installed in /mnt/d/gem5_simulator/build
, while its soruce are at /mnt/d/gem5_simulator/gem5
.
You can compile from scratch the toolchain for Risc-V following the instruction @ https://github.com/riscv-collab/riscv-gnu-toolchain
For linux users, you can intall the toolchain using you package manager. For example, for ubuntu users:
sudo apt install gcc-riscv64-linux-gnu
To install Gem5, you can follow the guidelines @ https://www.gem5.org/documentation/general_docs/building
Just remember that you need the following Gem5 characteristics to install:
- ISA = RISCV.
- variant = opt.
Be aware: the Gem5 compilation is very, very, very (did i already say very?!) time consuming.
To download Konata, visit the Konata github pages @ https://github.com/shioyadan/Konata/releases
Download the appropriate Konata release for your operating system. Konata is available for various platforms, including Windows, macOS, and Linux.
Unzip the release, inside you will find an executable named konata
or konata.exe
(OS dependent!).
Be aware: For windows/macOS users, you need to open the Konata application manually and load the trace
To simulate a program, run the simulate.sh
script with the desired program as an argument:
./simulate.sh -i ./programs/sanity_test/ -nogui
You can specify with -gui
or -nogui
the automatic opening of the Konata simulation (for linux users).
This will produce an ELF (Executable and Linkable Format) file in the programs/sanity_test/
directory.
Afterward, the ELF is passed to the Architectural Simulator, and program-related statistics (stats.txt
) and trace (trace.out
)are dumped in ./results/sanity_test/
The instruction trace, and the statistics are extractred only from a Region of Interest (ROI), as Figure below shows.
#ifdef _GEM5_
#include <gem5/m5ops.h>
#endif /*_GEM5_*/
int main() {
/********************************************************
***** Starting Region of Interest (ROI) ********
********************************************************/
#if _GEM5_
m5_work_begin(1,1);
#endif /*_GEM5_*/
// my c benchmark core
angle2time_conversion();
tooth_to_spark();
/********************************************************
***** End Region of Interest (ROI) ********
********************************************************/
#ifdef _GEM5_
m5_work_end(1,1);
#endif /*_GEM5_*/
return 0;
}
To visualize the pipeline, follow these steps:
-
Load the
trace.out
file onto Konata, a tool for visualizing gem5 traces. From the menu in the window or using drag and drop. -
Use Konata's interface to visualize and analyze the pipeline behavior of your simulated program.
Note For linux-based users you can directly launch the pipeline visualizer with the option -gui
option in simulate script
- Francesco Angione ([email protected])
- Giorgio Insinga ([email protected])
- Annachiara Ruospo ([email protected])