World's Fair 2025
How fast are LLM inference engines anyway? — Charles Frye, Modal
Overview
This talk explores the performance of open-source LLM inference engines, highlighting how recent advancements in model quality and inference software have made self-hosting viable. It presents benchmarking data to help engineers understand and optimize LLM performance for various use cases, emphasizing the trade-offs between different configurations and workloads.
Who should watch
- AI Engineers
- Product Managers
- Builders evaluating LLM deployment options
- Those interested in optimizing LLM inference speed and cost
- Individuals working with open-source LLMs
Key takeaways
- The quality and accessibility of open-source LLMs have significantly improved, making self-hosting a practical alternative to proprietary models for many applications.
- Modern inference engines incorporate advanced techniques like KV caching, paged attention, and speculative decoding, simplifying the deployment of performant LLMs.
- Benchmarking data reveals that workloads dominated by context processing (more tokens in) yield significantly higher throughput than those dominated by token generation (more tokens out).
- Using lower precision formats like FP8 or FP4 on compatible hardware can lead to substantial performance gains due to faster multiplication operations.
- Achieving high throughput often involves scaling out inference across multiple replicas rather than solely scaling up a single instance.
- The Modal LLM Almanac provides a resource for comparing inference speeds across different models and engines, with open-source code available for community contributions and further benchmarking.
- Optimizing for throughput-oriented tasks involving heavy arithmetic, like matrix multiplications, is key to maximizing GPU utilization.
- When latency is a concern, prioritizing context processing over complex reasoning can offer performance improvements without sacrificing time-to-first-token.
Notable quotes
*The situation has changed. It's really exciting. It sort of finally makes sense to self-host.*
*The requests per second that we're seeing here is about four requests per second for VLM on the same workload but with like context instead of generation.*
*The latency is like almost identical in time in time to first token even though we're doing 10 times as many tokens. Basically a free lunch.*
Unofficial community note. Prefer the recording for nuance.