[INFORMATION] mmyolo - Model Surgery using edgeai-modeloptimization - to create lite models

Introduction

mmyolo (https://github.com/open-mmlab/mmyolo) is a repository that has several interesting Object Detection models. For example, it includes models such as YOLOv5, YOLOv7, YOLOX, YOLOv8 etc.

Here we describe how to apply Model Surgery on mmyolo to create lite models that run faster on Embedded Systems.

Background - What actually happens in Model Surgery

The types of Operators/Layers that are being used in popular models are increasing rapidly. All of them may not work efficiently in embedded devices. For example, a ReLU activation layer is much faster compared to a SWish activation layer - because ReLU operator is implemented in Hardware at fullest speed (because of the simplicity of ReLU operation). This is just an example. There are several such examples.

In many cases it is possible to replace in-efficient layers with their efficient alternatives without actually modifying the code. It is done by modifying the Python model after the model has been instantiated.

How to use edgeai-modeloptimization

edgeai-modeloptimization (https://github.com/TexasInstruments/edgeai-tensorlab/tree/main/edgeai-modeloptimization) is a package that can automate some of the Model Surgery aspects.

It provides edgeai_torchmodelopt, a python pakage that helps to modify PyTorch models without manually editing the model code.

The exact location is here: https://github.com/TexasInstruments/edgeai-tensorlab/tree/main/edgeai-modeloptimization/torchmodelopt

It provides various types of model surgery options as described here: https://github.com/TexasInstruments/edgeai-tensorlab/blob/main/edgeai-modeloptimization/torchmodelopt/docs/surgery.md

Patch file

The commit id of mmyolo (https://github.com/open-mmlab/mmyolo) for this explanation is: 8c4d9dc503dc8e327bec8147e8dc97124052f693

This patch file includes above modification in train.py and other modifications in val.py, prototxt export etc. 0001-2024-Aug-2-mmyolo.commit-8c4d9dc5.-model-surgery-with-edgeai-modeloptimization.txt

Patching mmyolo:

git clone https://github.com/open-mmlab/mmyolo.git
git checkout 8c4d9dc5
git am 0001-mmyolo.commit-8c4d9dc5.-model-surgery-with-edgeai-modeloptimization.txt

Run training:

python3 tools/train.py <configfile> --model-surgery 1

You can also use tools/dist_train.sh (just make sure that --model-surgery 1 argument is passed inside it)

Expected Accuracy

This table shows expected model accuracy of Lite models after training.

Dataset	Original Model	Lite Model	Input Size	Original AP[0.5:0.95]%, AP50%	Lite AP[0.5:0.95]%, AP50%	GigaMACS	config file
	YOLOv5 models
COCO	YOLOv5-nano	YOLOv5-nano-lite	640x640	28.0, 45.9	25.2, 42.1	2.07	configs/yolov5/yolov5_n-v61_syncbn_fast_8xb16-300e_coco.py
COCO	YOLOv5-small	YOLOv5-small-lite	640x640	37.7, 57.1	35.5, 54.7	7.89	configs/yolov5/yolov5_s-v61_syncbn_fast_8xb16-300e_coco.py
	YOLOv7 models
COCO	YOLOv7-tiny	YOLOv7-tiny-lite	640x640	37.5, 55.8	36.7, 55.0	6.87	configs/yolov7/yolov7_tiny_syncbn_fast_8x16b-300e_coco.py
COCO	YOLOv7-large	YOLOv7-large-lite	640x640	51.0, 69.0	48.1, 66.4	52.95	configs/yolov7/yolov7_l_syncbn_fast_8x16b-300e_coco.py
	YOLOv8 models
COCO	YOLOv8-nano	YOLOv8-nano-lite	640x640	37.2, 52.7	34.5, 49.7	-	configs/yolov8/yolov8_n_syncbn_fast_8xb16-500e_coco.py
COCO	YOLOv8-small	YOLOv8-small-lite	640x640	44.2, 61.0	42.4, 58.8	14.33	configs/yolov8/yolov8_s_syncbn_fast_8xb16-500e_coco.py
	YOLOX models
COCO	YOLOX-tiny	YOLOX-tiny-lite	416x416	32.7, 50.3	31.1, 48.4	3.25	configs/yolox/yolox_tiny_fast_8xb8-300e_coco.py
COCO	YOLOX-small	YOLOX-small-lite	640x640	40.7, 59.6	38.7, 57.4	7.85	configs/yolox/yolox_s_fast_8xb8-300e_coco.py

Notes

GigaMACS: Complexity in Giga Multiply-Accumulations required for inference (lower is better). This is an important metric to watch out for when selecting models for embedded inference.
Accuracy for Object Detection on COCO dataset primarily uses two accuracy metrics AP[0.5:0.95] and AP50 (in percentages). AP[0.5:0.95] is the Mean of Average Precision values computed at IOUs ranging from 0.5 to 0.95 and averaged. AP50 is the Average Precision computed at 0.5 IoU. If only one accuracy metric is mentioned in a table cell, then it is AP[0.5:0.95]. Be sure to compare using the same metric when comparing across various detectors or configurations.
Input size in the tables (width x height) indicates the resolution for the model input. Original input images can be resized to that resolution with preserving the aspect ratio (may need padding) or without preserving the aspect ratio (depending on the flag keep_ratio in config files).

Additional information

Additional information about the details of the modifications done using Model Surgery is here: https://github.com/TexasInstruments/edgeai-yolov5

How Model Surgery is actually done

This is for information only - the above patch already includes these changes.

The patch adds the following code in mmyolo repository in tools/train.py. similarly tools/test.py is also modified to include model surgery.

from edgeai_torchmodelopt import xmodelopt

Add this in parse_args function:

    parser.add_argument('--model-surgery', type=int, default=0)

Add the following code in mmyolo repository in tools/train.py before the line runner.train()

if args.model_surgery:
    surgery_fn = xmodelopt.surgery.v1.convert_to_lite_model if args.model_surgery == 1 \
                 else (xmodelopt.surgery.v2.convert_to_lite_fx if args.model_surgery == 2 else None)

    runner._init_model_weights()
    if is_model_wrapper(runner.model):
        runner.model = runner.model.module
    runner.model.backbone = surgery_fn(runner.model.backbone)
    runner.model.neck = surgery_fn(runner.model.neck)
    # Only head_module of head goes through model_surgery as it contains all compute layers
    if not isinstance(runner.model.bbox_head.head_module, (YOLOv5HeadModule, YOLOv7HeadModule, YOLOv8HeadModule, YOLOv6HeadModule)):
        if hasattr(runner.model.bbox_head.head_module, 'reg_max'):
            reg_max = runner.model.bbox_head.head_module.reg_max
        else:
            reg_max = None
        runner.model.bbox_head.head_module = \
            surgery_fn(runner.model.bbox_head.head_module)
        if reg_max is not None:
            runner.model.bbox_head.head_module.reg_max = reg_max
    elif isinstance(runner.model.bbox_head.head_module, (YOLOv8HeadModule, YOLOv6HeadModule)):
        runner.model.bbox_head.head_module = xmodelopt.surgery.v1.convert_to_lite_model(runner.model.bbox_head.head_module)
    runner.model = runner.wrap_model(runner.cfg.get('model_wrapper_cfg'), runner.model)
print("\n\n model summary : \n",runner.model)

TexasInstruments / edgeai-tensorlab