Executing a Tiny Model with TVMC Micro¶
Author: Mehrdad Hessar
This tutorial explains how to compile a tiny model for a micro device, build a program on Zephyr platform to execute this model, flash the program and run the model all using tvmc micro command.
This tutorial is explaining using TVMC Mirco on Zephyr platform. You need to install Zephyr dependencies before processing with this tutorial. Alternatively, you can run this tutorial in one of the following ways which has Zephyr depencencies already installed.
Use QEMU docker image provided by TVM. Following these you will download and login to the docker image:
cd tvm ./docker/bash.sh tlcpack/ci-qemu
Using TVMC Micro¶
TVMC is a command-line tool which is installed as a part of TVM Python packages. Accessing this package varies based on your machine setup. In many cases, you can use the
tvmccommand directly. Alternatively, if you have TVM as a Python module on your
$PYTHONPATH, you can access this driver with
python -m tvm.driver.tvmccommand. This tutorial will use TVMC command as
To check if you have TVMC command installed on your machine, you can run:tvmc --help
To compile a model for microtvm we use
tvmc compilesubcommand. The output of this command is used in next steps with
tvmc microsubcommands. You can check the availability of TVMC Micro using:tvmc micro --help
The main tasks that you can perform using
flash. To read about specific options under a givern subcommand, use
tvmc micro <subcommand> --help. We will use each subcommand in this tutorial.
Obtain a Tiny Model¶
For this tutorial, we will use Magic Wand model from tflite micro. Magic Wand is a Depthwise Convolution Layer model which recognizes gestures with an accelerometer.
For this tutorial we will be using the model in tflite format.wget https://github.com/tensorflow/tflite-micro/raw/main/tensorflow/lite/micro/examples/magic_wand/magic_wand.tflite
Compiling a TFLite model to a Model Library Format¶
Model Library Format (MLF) is an output format that TVM provides for micro targets. MLF is a tarball containing a file for each piece of the TVM compiler output which can be used on micro targets outside TVM environment. Read more about Model Library Format.
Here, we generate a MLF file for
qemu_x86Zephyr board. To generate MLF output for the
magic_wandtflite model:tvmc compile magic_wand.tflite \ --target='c -keys=cpu -link-params=0 -model=host' \ --runtime=crt \ --runtime-crt-system-lib 1 \ --executor='graph' \ --executor-graph-link-params 0 \ --output model.tar \ --output-format mlf \ --pass-config tir.disable_vectorize=1 \ --disabled-pass=AlterOpLayout
This will generate a
model.tarfile which contains TVM compiler output files. To run this command for a different Zephyr device, you need to update
target. For instance, for
nrf5340dk_nrf5340_cpuappboard the target is
--target='c -keys=cpu -link-params=0 -model=nrf5340dk'.
Create a Zephyr Project Using Model Library Format¶
To generate a Zephyr project we use TVM Micro subcommand
create. We pass the MLF format and the path for the project to
createsubcommand along with project options. Project options for each platform (Zephyr/Arduino) are defined in their Project API server file. To generate Zephyr project, run:tvmc micro create \ project \ model.tar \ zephyr \ --project-option project_type=host_driven zephyr_board=qemu_x86
This will generate a
Host-DrivenZephyr project for
qemu_x86Zephyr board. In Host-Driven template project, the Graph Executor will run on host and perform the model execution on Zephyr device by issuing commands to the device using an RPC mechanism. Read more about Host-Driven Execution.
To get more information about TVMC Micro
createsubcommand:tvmc micro create --help
Build and Flash Zephyr Project Using TVMC Micro¶
Next step is to build the Zephyr project which includes TVM generated code for running the tiny model, Zephyr template code to run a model in Host-Driven mode and TVM runtime source/header files. To build the project:tvmc micro build \ project \ zephyr \ --project-option zephyr_board=qemu_x86
This will build the project in
projectdirectory and generates binary files under
project/build. To build Zephyr project for a different Zephyr board, change
Next, we flash the Zephyr binary file to Zephyr device. For
qemu_x86Zephyr board this step does not actually perform any action since QEMU will be used, however you need this step for physical hardware.tvmc micro flash \ project \ zephyr \ --project-option zephyr_board=qemu_x86
Run Tiny Model on Micro Target¶
After flashing the device, the compiled model and TVM RPC server are programmed on the device. The Zephyr board is waiting for host to open a communication channel. MicroTVM devices typicall communicate using a serial communication (UART). To run the flashed model on the device using TVMC, we use
tvmc runsubcommand and pass
--device microto specify the device type. This command will open a communication channel, set input values using
Graph Executoron host and run full model on the device. Then it gets output from the device.tvmc run \ --device micro \ project \ --project-option zephyr_board=qemu_x86 \ --fill-mode ones \ --print-top 4 # Output: # # INFO:__main__:b'[100%] [QEMU] CPU: qemu32,+nx,+pae\n' # remote: microTVM Zephyr runtime - running # INFO:__main__:b'[100%] Built target run\n' # [[3. 1. 2. 0. ] # [0.47213247 0.41364592 0.07525456 0.03896701]]
Specifically, this command sets the input of the model to all ones and shows the four values of the output with their indices.