cavatools

RISC-V instruction set simulator and performance analysis tools

Cavatools simulates a multi-core RISC-V machine. The simulator runs on X86 Linux host and presents a user-mode multi-threaded Linux interface to the guest program. Standard RISC-V tool chain (GNU or LLVM) with GLIBC is used to compile the guest program. All host Linux system calls are available to the guest program. Multi-threaded guest programs compiled with Pthead and OpenMP are supported. Cavatools has several parts:

• uspike is a RISC-V instruction set interpreter. Python scripts extract instruction bit encoding and execution semantics from the official GitHub repository.
• caveat is a performance simulator. Currently it models a multicore chip with single-issue in-order pipelines and private instruction and data level-1 caches.
• erised is a real-time performance viewer for caveat while the guest program is running. For each static instruction erised shows the execution frequency, cycles per instruction, instruction and cache misses while the program is running.

Prerequisites

Environment variable RVTOOLS should be path to the riscv-tools tree. The subtrees are:

riscv-tools/riscv-opcodes       [from https://github.com/riscv/riscv-opcodes commit 7c3db437d8d3b6961f8eb2931792eaea1c469ff3]
riscv-tools/riscv-isa-sim       [from https://github.com/riscv-software-src/riscv-isa-sim commit 761629f197600246226b905f97e0ae62a82ff6af]
riscv-tools/riscv-pk            [from https://github.com/riscv-software-src/riscv-pk commit 97b683ed3cbeeb059e5ad3de8f884db734447d56]
riscv-tools/riscv-gnu-toolchain [from https://github.com/riscv-collab/riscv-gnu-toolchain]

You need to build at least riscv-isa-sim (spike) because uspike links to libraries there. RVTOOLS defaults to /opt/riscv-tools.

Getting the sources

The repository is on GitHub:

$ git clone https://github.com/phaa-eu/cavatools

Installation

Environment variable CAVA is installation path, default to home directory $(HOME). To build Cavatools:

$ cd cavatools
$ make install

The following files are installed:

uspike, caveat, erised in $(CAVA)/bin/
libcava.a in $(CAVA)/lib/
several .h files in $(CAVA)/include/cava

Include $(CAVA)/bin in $(PATH) to run Cavatools programs.

Running Cavatools

Programs should be compiled -static using the Linux/glibc riscv-gnu-toolchain:

$ riscv64-unknown-linux-gnu-gcc -static ... testpgm.c -o testpgm

To execute a RISC-V program without simulation:

$ uspike testpgm <any number of flags and arguments to testpgm>

To see instruction execution performance in real time run in one window:

$ caveat testpgm <any number of flags and arguments to testpgm>

and this in another window:

$ erised testpgm

Shared memory segment /dev/shm/caveat (filename can be changed with option) containing counters is created. Erised passively reads /dev/shm/caveat and displays performance data in its window, controlled interactively by mouse.