Lookup the KV cache#
The lookup
interface is defined as the following:
lookup(tokens: List[int]) -> layout_info: Dict[str, Tuple[str, int]]
The function takes a list of tokens as input and returns a dictionary containing the layout information for each token.
The layout information is represented as a mapping between instance_id
and a tuple of (location, matched_prefix_length)
.
Example usage:#
First, we need to start the lmcache controller at port 9000 and the monitor at port 9001:
python -m lmcache.controller --port 9000 --monitor_port 9001
Second, we need a yaml file example.yaml
to properly configure the lmcache instance:
chunk_size: 256
local_cpu: True
max_local_cpu_size: 5
# cache controller configurations
enable_controller: True
lmcache_instance_id: "lmcache_default_instance"
controller_url: "localhost:9001"
lmcache_worker_url: "localhost:8001"
Third, we need to start the vllm/lmcache instance:
LMCACHE_USE_EXPERIMENTAL=True LMCACHE_CONFIG_FILE=example.yaml vllm serve meta-llama/Meta-Llama-3.1-8B-Instruct --max-model-len 4096 --gpu-memory-utilization 0.8 --port 8000 --kv-transfer-config '{"kv_connector":"LMCacheConnectorV1", "kv_role":"kv_both"}'
Then, we can send a request to vllm:
curl -X POST http://localhost:8000/v1/completions \
-H "Content-Type: application/json" \
-d '{
"model": "meta-llama/Meta-Llama-3.1-8B-Instruct",
"prompt": "Explain the significance of KV cache in language models.",
"max_tokens": 10
}'
Finally, we can send a lookup
request to the lmcache controller:
curl -X POST http://localhost:9000/lookup \
-H "Content-Type: application/json" \
-d '{
"tokens": [128000, 849, 21435, 279, 26431, 315, 85748, 6636, 304, 4221, 4211, 13]
}'
We should be able to see the response like this:
{"lmcache_default_instance_id": ("cpu", 12)}
This means that the KV cache for the given tokens is stored in lmcache_default_instance
’s CPU memory and the matched prefix length is 12.