OpenVINO™ GenAI Library

OpenVINO™ GenAI is a flavor of OpenVINO™, aiming to simplify running inference of generative AI models. It hides the complexity of the generation process and minimizes the amount of code required.

Install OpenVINO™ GenAI

The OpenVINO™ GenAI flavor is available for installation via Archive and PyPI distributions. To install OpenVINO™ GenAI, refer to the Install Guide.

To build OpenVINO™ GenAI library from source, refer to the Build Instructions.

Usage

Prerequisites

1. Installed OpenVINO™ GenAI

   If OpenVINO GenAI is installed via archive distribution or built from source, you will need to install additional python dependencies (e.g. optimum-cli for simplified model downloading and exporting, it's not required to install ./samples/requirements.txt for deployment if the model has already been exported):

   # (Optional) Clone OpenVINO GenAI repository if it does not exist
   git clone --recursive https://github.com/openvinotoolkit/openvino.genai.git
   cd openvino.genai
   # Install python dependencies
   python -m pip install ./thirdparty/openvino_tokenizers/[transformers] --extra-index-url https://storage.openvinotoolkit.org/simple/wheels/pre-release
   python -m pip install --upgrade-strategy eager -r ./samples/requirements.txt
   

2. A model in OpenVINO IR format

   Download and convert a model with optimum-cli:

   optimum-cli export openvino --model "TinyLlama/TinyLlama-1.1B-Chat-v1.0" --trust-remote-code "TinyLlama-1.1B-Chat-v1.0"
   

LLMPipeline is the main object used for decoding. You can construct it straight away from the folder with the converted model. It will automatically load the main model, tokenizer, detokenizer and default generation configuration.

Python

A simple example:

import openvino_genai as ov_genai
pipe = ov_genai.LLMPipeline(model_path, "CPU")
print(pipe.generate("The Sun is yellow because", max_new_tokens=100))

Calling generate with custom generation config parameters, e.g. config for grouped beam search:

import openvino_genai as ov_genai
pipe = ov_genai.LLMPipeline(model_path, "CPU")

result = pipe.generate("The Sun is yellow because", max_new_tokens=100, num_beam_groups=3, num_beams=15, diversity_penalty=1.5)
print(result)

output:

'it is made up of carbon atoms. The carbon atoms are arranged in a linear pattern, which gives the yellow color. The arrangement of carbon atoms in'

A simple chat in Python:

import openvino_genai as ov_genai
pipe = ov_genai.LLMPipeline(model_path)

config = {'max_new_tokens': 100, 'num_beam_groups': 3, 'num_beams': 15, 'diversity_penalty': 1.5}
pipe.set_generation_config(config)

pipe.start_chat()
while True:
    print('question:')
    prompt = input()
    if prompt == 'Stop!':
        break
    print(pipe(prompt, max_new_tokens=200))
pipe.finish_chat()

Test to compare with Huggingface outputs

C++

A simple example:

#include "openvino/genai/llm_pipeline.hpp"
#include <iostream>

int main(int argc, char* argv[]) {
    std::string model_path = argv[1];
    ov::genai::LLMPipeline pipe(model_path, "CPU");
    std::cout << pipe.generate("The Sun is yellow because", ov::genai::max_new_tokens(256));
}

Using group beam search decoding:

#include "openvino/genai/llm_pipeline.hpp"
#include <iostream>

int main(int argc, char* argv[]) {
    std::string model_path = argv[1];
    ov::genai::LLMPipeline pipe(model_path, "CPU");

    ov::genai::GenerationConfig config;
    config.max_new_tokens = 256;
    config.num_beam_groups = 3;
    config.num_beams = 15;
    config.diversity_penalty = 1.0f;

    std::cout << pipe.generate("The Sun is yellow because", config);
}

A simple chat in C++ using grouped beam search decoding:

#include "openvino/genai/llm_pipeline.hpp"
#include <iostream>

int main(int argc, char* argv[]) {
    std::string prompt;

    std::string model_path = argv[1];
    ov::genai::LLMPipeline pipe(model_path, "CPU");
    
    ov::genai::GenerationConfig config;
    config.max_new_tokens = 100;
    config.num_beam_groups = 3;
    config.num_beams = 15;
    config.diversity_penalty = 1.0f;
    
    pipe.start_chat();
    for (;;;) {
        std::cout << "question:\n";
        std::getline(std::cin, prompt);
        if (prompt == "Stop!")
            break;

        std::cout << "answer:\n";
        auto answer = pipe(prompt, config);
        std::cout << answer << std::endl;
    }
    pipe.finish_chat();
}

Streaming example with lambda function:

#include "openvino/genai/llm_pipeline.hpp"
#include <iostream>

int main(int argc, char* argv[]) {
    std::string model_path = argv[1];
    ov::genai::LLMPipeline pipe(model_path, "CPU");
        
    auto streamer = [](std::string word) { 
        std::cout << word << std::flush; 
        // Return flag corresponds whether generation should be stopped.
        // false means continue generation.
        return false;
    };
    std::cout << pipe.generate("The Sun is yellow bacause", ov::genai::streamer(streamer), ov::genai::max_new_tokens(200));
}

Streaming with a custom class:

#include "openvino/genai/streamer_base.hpp"
#include "openvino/genai/llm_pipeline.hpp"
#include <iostream>

class CustomStreamer: public ov::genai::StreamerBase {
public:
    bool put(int64_t token) {
        bool stop_flag = false; 
        /* 
        custom decoding/tokens processing code
        tokens_cache.push_back(token);
        std::string text = m_tokenizer.decode(tokens_cache);
        ...
        */
        return stop_flag;  // flag whether generation should be stoped, if true generation stops.
    };

    void end() {
        /* custom finalization */
    };
};

int main(int argc, char* argv[]) {
    CustomStreamer custom_streamer;

    std::string model_path = argv[1];
    ov::genai::LLMPipeline pipe(model_path, "CPU");
    std::cout << pipe.generate("The Sun is yellow because", ov::genai::streamer(custom_streamer), ov::genai::max_new_tokens(200));
}

Performance Metrics

openvino_genai.PerfMetrics (referred as PerfMetrics for simplicity) is a structure that holds performance metrics for each generate call. PerfMetrics holds fields with mean and standard deviations for the following metrics:

• Time To the First Token (TTFT), ms
• Time per Output Token (TPOT), ms/token
• Generate total duration, ms
• Tokenization duration, ms
• Detokenization duration, ms
• Throughput, tokens/s

and:

• Load time, ms
• Number of generated tokens
• Number of tokens in the input prompt

Performance metrics are stored either in the DecodedResults or EncodedResults perf_metric field. Additionally to the fields mentioned above, PerfMetrics has a member raw_metrics of type openvino_genai.RawPerfMetrics (referred to as RawPerfMetrics for simplicity) that contains raw values for the durations of each batch of new token generation, tokenization durations, detokenization durations, and more. These raw metrics are accessible if you wish to calculate your own statistical values such as median or percentiles. However, since mean and standard deviation values are usually sufficient, we will focus on PerfMetrics.

import openvino_genai as ov_genai
pipe = ov_genai.LLMPipeline(model_path, "CPU")
result = pipe.generate(["The Sun is yellow because"], max_new_tokens=20)
perf_metrics = result.perf_metrics

print(f'Generate duration: {perf_metrics.get_generate_duration().mean:.2f}')
print(f'TTFT: {perf_metrics.get_ttft().mean:.2f} ms')
print(f'TPOT: {perf_metrics.get_tpot().mean:.2f} ms/token')
print(f'Throughput: {perf_metrics.get_throughput()get_.mean():.2f} tokens/s')

#include "openvino/genai/llm_pipeline.hpp"
#include <iostream>

int main(int argc, char* argv[]) {
    std::string model_path = argv[1];
    ov::genai::LLMPipeline pipe(model_path, "CPU");
    auto result = pipe.generate("The Sun is yellow because", ov::genai::max_new_tokens(20));
    auto perf_metrics = result.perf_metrics;
    
    std::cout << std::fixed << std::setprecision(2);
    std::cout << "Generate duration: " << perf_metrics.get_generate_duration().mean << " ms" << std::endl;
    std::cout << "TTFT: " << metrics.get_ttft().mean  << " ms" << std::endl;
    std::cout << "TPOT: " << metrics.get_tpot().mean  << " ms/token " << std::endl;
    std::cout << "Throughput: " << metrics.get_throughput().mean  << " tokens/s" << std::endl;
}

output:

mean_generate_duration: 76.28
mean_ttft: 42.58
mean_tpot 3.80

Note: If the input prompt is just a string, the generate function returns only a string without perf_metrics. To obtain perf_metrics, provide the prompt as a list with at least one element or call generate with encoded inputs.

Several perf_metrics can be added to each other. In that case raw_metrics are concatenated and mean/std values are recalculated. This accumulates statistics from several generate() calls

#include "openvino/genai/llm_pipeline.hpp"
#include <iostream>

int main(int argc, char* argv[]) {
    std::string model_path = argv[1];
    ov::genai::LLMPipeline pipe(model_path, "CPU");
    auto result_1 = pipe.generate("The Sun is yellow because", ov::genai::max_new_tokens(20));
    auto result_2 = pipe.generate("The Sun is yellow because", ov::genai::max_new_tokens(20));
    auto perf_metrics = result_1.perf_metrics + result_2.perf_metrics
    
    std::cout << std::fixed << std::setprecision(2);
    std::cout << "Generate duration: " << perf_metrics.get_generate_duration().mean << " ms" << std::endl;
    std::cout << "TTFT: " << metrics.get_ttft().mean  << " ms" << std::endl;
    std::cout << "TPOT: " << metrics.get_tpot().mean  << " ms/token " << std::endl;
    std::cout << "Throughput: " << metrics.get_throughput().mean  << " tokens/s" << std::endl;
}

import openvino_genai as ov_genai
pipe = ov_genai.LLMPipeline(model_path, "CPU")
res_1 = pipe.generate(["The Sun is yellow because"], max_new_tokens=20)
res_2 = pipe.generate(["Why Sky is blue because"], max_new_tokens=20)
perf_metrics = res_1.perf_metrics + res_2.perf_metrics

print(f'Generate duration: {perf_metrics.get_generate_duration().mean:.2f}')
print(f'TTFT: {perf_metrics.get_ttft().mean:.2f} ms')
print(f'TPOT: {perf_metrics.get_tpot().mean:.2f} ms/token')
print(f'Throughput: {perf_metrics.get_throughput().mean:.2f} tokens/s')

For more examples of how metrics are used, please refer to the Python benchmark_genai.py and C++ benchmark_genai samples.

How It Works

For information on how OpenVINO™ GenAI works, refer to the How It Works Section.

Supported Models

For a list of supported models, refer to the Supported Models Section.