This utility extracts the KV cache scaling factors from a quantized HF (Hugging Face) model. The extracted scaling factors are saved to a JSON file, which can later be used by vLLM (variable-length language model) during runtime. This tool is particularly useful when the KV cache data type is FP8 and is intended for use on ROCm (AMD GPU) platforms.
## Prerequisites
- Python 3.x
- PyTorch
- NumPy
- Hugging Face Transformers
- Hugging Face Hub
- AMMO
Before incorporating the FP8 datatype for inference workloads, you must adhere to the following steps:
1. Install all necessary prerequisites and dependencies.
2. Convert HF model into a quantized HF model.
3. Extract KV Cache Scaling Factors from quantized HF model.
4. Load KV Cache Scaling Factors into VLLM.
### 2. Convert HF model into a quantized HF model.
Note: The following steps are adapted from the [TensorRT-LLM repository](https://github.com/NVIDIA/TensorRT-LLM/blob/main/examples/quantization/README.md).
`quantize.py` (examples/fp8/quantizer/quantize.py) uses the quantization toolkit (AMMO) to calibrate the PyTorch models and export TensorRT-LLM checkpoints. Each TensorRT-LLM checkpoint contains a config file (in .json format) and one or several rank weight files (in .safetensors format).
The detailed quantization toolkit (AMMO) conversion guide for FP8 can be found at `examples/fp8/quantizer/README.md`.
`extract_scales.py` (examples/fp8/extract_scales.py) can be utilized to extract the KV cache scaling factors from your quantized HF model, however at the moment, this tool exclusively supports Llama 2 models. It is also important to note the following:
1.**File Structure**: The utility operates under the assumption that all parameters, including KV cache scaling factors, corresponding to a particular Tensor Parallelism (TP) rank are stored in a single file. These files must adhere to a specific naming convention where the TP rank is immediately identified after a specific keyword (e.g., "rank") in the filename.
2.**TP Decomposition**: The utility assumes consistency between the TP decomposition employed by the quantizer tool and that used by vLLM.
3.**AMMO Compatibility**: Currently, the generated KV cache scaling factors for AMMO remain uniform across all TP ranks.
This script evaluates the inference throughput of language models using various backends such as vLLM. It measures the time taken to process a given number of prompts and generate sequences for each prompt. The recently generated KV cache scaling factors are now integrated into the benchmarking process and allow for KV cache scaling factors to be utilized for FP8.
"""Create a list of test prompts with their sampling parameters.
2 requests for base model, 4 requests for the LoRA. We define 2
different LoRA adapters (using the same model for demo purposes).
Since we also set `max_loras=1`, the expectation is that the requests
with the second LoRA adapter will be ran after all requests with the
first adapter have finished.
"""
return[
("A robot may not injure a human being",
SamplingParams(temperature=0.0,
logprobs=1,
prompt_logprobs=1,
max_tokens=128),None),
("To be or not to be,",
SamplingParams(temperature=0.8,
top_k=5,
presence_penalty=0.2,
max_tokens=128),None),
(
"[user] Write a SQL query to answer the question based on the table schema.\n\n context: CREATE TABLE table_name_74 (icao VARCHAR, airport VARCHAR)\n\n question: Name the ICAO for lilongwe international airport [/user] [assistant]",# noqa: E501
SamplingParams(temperature=0.0,
logprobs=1,
prompt_logprobs=1,
max_tokens=128,
stop_token_ids=[32003]),
LoRARequest("sql-lora",1,lora_path)),
(
"[user] Write a SQL query to answer the question based on the table schema.\n\n context: CREATE TABLE table_name_11 (nationality VARCHAR, elector VARCHAR)\n\n question: When Anchero Pantaleone was the elector what is under nationality? [/user] [assistant]",# noqa: E501
SamplingParams(n=3,
best_of=3,
use_beam_search=True,
temperature=0,
max_tokens=128,
stop_token_ids=[32003]),
LoRARequest("sql-lora",1,lora_path)),
(
"[user] Write a SQL query to answer the question based on the table schema.\n\n context: CREATE TABLE table_name_74 (icao VARCHAR, airport VARCHAR)\n\n question: Name the ICAO for lilongwe international airport [/user] [assistant]",# noqa: E501
SamplingParams(temperature=0.0,
logprobs=1,
prompt_logprobs=1,
max_tokens=128,
stop_token_ids=[32003]),
LoRARequest("sql-lora2",2,lora_path)),
(
"[user] Write a SQL query to answer the question based on the table schema.\n\n context: CREATE TABLE table_name_11 (nationality VARCHAR, elector VARCHAR)\n\n question: When Anchero Pantaleone was the elector what is under nationality? [/user] [assistant]",# noqa: E501
SamplingParams(n=3,
best_of=3,
use_beam_search=True,
temperature=0,
max_tokens=128,
stop_token_ids=[32003]),
LoRARequest("sql-lora",1,lora_path)),
]
defprocess_requests(engine:LLMEngine,
test_prompts:List[Tuple[str,SamplingParams,
Optional[LoRARequest]]]):
"""Continuously process a list of prompts and handle the outputs."""