diff --git a/README.md b/README.md index 8d2ebc601e..f11d12c525 100644 --- a/README.md +++ b/README.md @@ -359,6 +359,10 @@ python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --port ``` python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --port 30000 --tp 2 ``` +- Add `--dp 2` to enable data parallelism. It can also be used together with tp. Data parallelism is better for throughput if there is enough memory. +``` +python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --port 30000 --dp 2 --tp 2 +``` - If you see out-of-memory errors during serving, please try to reduce the memory usage of the KV cache pool by setting a smaller value of `--mem-fraction-static`. The default value is `0.9` ``` python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --port 30000 --mem-fraction-static 0.7 diff --git a/docs/hyperparameter_tuning.md b/docs/hyperparameter_tuning.md new file mode 100644 index 0000000000..8246374305 --- /dev/null +++ b/docs/hyperparameter_tuning.md @@ -0,0 +1,30 @@ +# Guide on Hyperparameter Tuning + +## Achieving Peak Throughput + +Achieving a large batch size is the most important thing for attaining high throughput. + +When the server is running at full load, look for the following in the log: +```[gpu_id=0] #running-req: 233, #token: 370959, token usage: 0.82, gen throughput (token/s): 4594.01, #queue-req: 417``` + +### Tune Your Request Submission Speed +`#queue-req` indicates the number of requests in the queue. If you frequently see `#queue-req == 0`, it suggests you are bottlenecked by the request submission speed. +A healthy range for `#queue-req` is `100 - 3000`. + +### Tune `--schedule-conservativeness` +`token usage` indicates the KV cache memory utilization of the server. `token usage > 0.9` means good utilization. +If you frequently see `token usage < 0.9` and `#queue-req > 0`, it means the server is too conservative about taking in new requests. You can decrease `--schedule-conservativeness` to a value like 0.5. +The case of serving being too conservative can happen when users send many requests with a large `max_new_tokens` but the requests stop very early due to EOS or stop strings. + +On the other hand, if you see `token usage` very high and you frequently see warnings like +`decode out of memory happened, #retracted_reqs: 1, #new_token_ratio: 0.9998 -> 1.0000`, you can increase `--schedule-conservativeness` to a value like 1.3. + +### Tune `--dp-size` and `--tp-size` +Data parallelism is better for throughput. When there is enough GPU memory, always favor data parallelism for throughput. + +### (Minor) Tune `--schedule-heuristic` +If you have many shared prefixes, use the default `--schedule-heuristic lpm`. `lpm` stands for longest prefix match. +When you have no shared prefixes at all, you can try `--schedule-heuristic fcfs`. `fcfs` stands for first come first serve. + +### (Minor) Tune `--max-prefill-tokens`, `--mem-fraction-static`, `--max-running-requests`. +If you see out of memory errors, you can decrease them. Otherwise, the default value should work well. \ No newline at end of file