[Core][5/N] Fully working chunked prefill e2e (#3884)

tests/distributed/test_chunked_prefill_distributed.py

@@ -0,0 +1,66 @@
+"""Compare the outputs of HF and distributed vLLM when using greedy sampling.
+vLLM will allocate all the available memory, so we need to run the tests one
+by one. The solution is to pass arguments (model name) by environment
+variables.
+
+Run:
+```sh
+TEST_DIST_MODEL=facebook/opt-125m pytest \
+    test_chunked_prefill_distributed.py
+TEST_DIST_MODEL=meta-llama/Llama-2-7b-hf \
+    test_chunked_prefill_distributed.py
+```
+"""
+import os
+
+import pytest
+import torch
+
+MODELS = [
+    os.environ["TEST_DIST_MODEL"],
+]
+
+
+@pytest.mark.skipif(torch.cuda.device_count() < 2,
+                    reason="Need at least 2 GPUs to run the test.")
+@pytest.mark.parametrize("model", MODELS)
+@pytest.mark.parametrize("dtype", ["half"])
+@pytest.mark.parametrize("max_tokens", [5])
+@pytest.mark.parametrize("chunked_prefill_token_size", [16])
+def test_models(
+    hf_runner,
+    vllm_runner,
+    example_prompts,
+    model: str,
+    dtype: str,
+    max_tokens: int,
+    chunked_prefill_token_size: int,
+) -> None:
+    # Add a chunked prefill config.
+    max_num_seqs = min(chunked_prefill_token_size, 256)
+    assert chunked_prefill_token_size != -1
+    enable_chunked_prefill = True
+    max_num_batched_tokens = chunked_prefill_token_size
+
+    hf_model = hf_runner(model, dtype=dtype)
+    hf_outputs = hf_model.generate_greedy(example_prompts, max_tokens)
+    del hf_model
+
+    vllm_model = vllm_runner(
+        model,
+        dtype=dtype,
+        tensor_parallel_size=2,
+        max_num_seqs=max_num_seqs,
+        enable_chunked_prefill=enable_chunked_prefill,
+        max_num_batched_tokens=max_num_batched_tokens,
+    )
+    vllm_outputs = vllm_model.generate_greedy(example_prompts, max_tokens)
+    del vllm_model
+
+    for i in range(len(example_prompts)):
+        hf_output_ids, hf_output_str = hf_outputs[i]
+        vllm_output_ids, vllm_output_str = vllm_outputs[i]
+        assert hf_output_str == vllm_output_str, (
+            f"Test{i}:\nHF: {hf_output_str!r}\nvLLM: {vllm_output_str!r}")
+        assert hf_output_ids == vllm_output_ids, (
+            f"Test{i}:\nHF: {hf_output_ids}\nvLLM: {vllm_output_ids}")