Principle:LMCache LMCache Engine Configuration
| Knowledge Sources | |
|---|---|
| Domains | Infrastructure, Configuration |
| Last Updated | 2026-02-09 00:00 GMT |
Overview
A configuration management pattern that initializes and validates runtime parameters for a KV cache engine from YAML files, environment variables, and programmatic overrides.
Description
Engine Configuration is the process of defining runtime parameters for the LMCache cache engine. It combines multiple configuration sources (YAML files, environment variables prefixed with LMCACHE_, and Python dictionary overrides) into a single validated configuration object. The configuration system uses a dynamic class creation pattern where field definitions are stored in a central dictionary, and the class is generated at runtime using a metaclass-like factory function.
This approach solves the problem of managing many interdependent parameters across different deployment scenarios (local offloading, disaggregated prefill, P2P sharing, CacheBlend) with a single unified configuration system. Configuration validation ensures that mutually exclusive options are caught early.
Usage
Use this principle when deploying LMCache in any mode. It is the first step in every workflow: before creating a cache engine, initializing a vLLM connector, or launching a controller, you must configure the engine. The configuration determines which storage backends are active (CPU, disk, remote), what chunk size to use, and which advanced features (blending, P2P, disaggregated prefill) are enabled.
Theoretical Basis
The configuration system follows the layered configuration pattern:
- Default values defined in the configuration schema
- YAML file overrides defaults (loaded via LMCACHE_CONFIG_FILE env var or explicit path)
- Environment variables override YAML (LMCACHE_CHUNK_SIZE, LMCACHE_LOCAL_CPU, etc.)
- Programmatic overrides override everything (dictionary passed at runtime)
After merging, validation runs to enforce constraints:
- If enable_blending=True, save_unfull_chunk is auto-set to True
- If enable_p2p=True, controller fields must be set
- If enable_pd=True, pd_role, pd_buffer_size, pd_buffer_device must be set