From ae80cfaf44e9df12355997cf594841fb89442fb2 Mon Sep 17 00:00:00 2001
From: admin9webs <admin@9webs.online>
Date: Fri, 10 Jul 2026 16:10:35 +0800
Subject: [PATCH] Add archived/vllm

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+---
+name: serving-llms-vllm
+description: "vLLM: high-throughput LLM serving, OpenAI API, quantization."
+version: 1.0.0
+author: Orchestra Research
+license: MIT
+dependencies: [vllm, torch, transformers]
+platforms: [linux, macos]
+metadata:
+  hermes:
+    tags: [vLLM, Inference Serving, PagedAttention, Continuous Batching, High Throughput, Production, OpenAI API, Quantization, Tensor Parallelism]
+
+---
+
+# vLLM - High-Performance LLM Serving
+
+## When to use
+
+Use when deploying production LLM APIs, optimizing inference latency/throughput, or serving models with limited GPU memory. Supports OpenAI-compatible endpoints, quantization (GPTQ/AWQ/FP8), and tensor parallelism.
+
+## Quick start
+
+vLLM achieves 24x higher throughput than standard transformers through PagedAttention (block-based KV cache) and continuous batching (mixing prefill/decode requests).
+
+**Installation**:
+```bash
+pip install vllm
+```
+
+**Basic offline inference**:
+```python
+from vllm import LLM, SamplingParams
+
+llm = LLM(model="meta-llama/Llama-3-8B-Instruct")
+sampling = SamplingParams(temperature=0.7, max_tokens=256)
+
+outputs = llm.generate(["Explain quantum computing"], sampling)
+print(outputs[0].outputs[0].text)
+```
+
+**OpenAI-compatible server**:
+```bash
+vllm serve meta-llama/Llama-3-8B-Instruct
+
+# Query with OpenAI SDK
+python -c "
+from openai import OpenAI
+client = OpenAI(base_url='http://localhost:8000/v1', api_key='EMPTY')
+print(client.chat.completions.create(
+    model='meta-llama/Llama-3-8B-Instruct',
+    messages=[{'role': 'user', 'content': 'Hello!'}]
+).choices[0].message.content)
+"
+```
+
+## Common workflows
+
+### Workflow 1: Production API deployment
+
+Copy this checklist and track progress:
+
+```
+Deployment Progress:
+- [ ] Step 1: Configure server settings
+- [ ] Step 2: Test with limited traffic
+- [ ] Step 3: Enable monitoring
+- [ ] Step 4: Deploy to production
+- [ ] Step 5: Verify performance metrics
+```
+
+**Step 1: Configure server settings**
+
+Choose configuration based on your model size:
+
+```bash
+# For 7B-13B models on single GPU
+vllm serve meta-llama/Llama-3-8B-Instruct \
+  --gpu-memory-utilization 0.9 \
+  --max-model-len 8192 \
+  --port 8000
+
+# For 30B-70B models with tensor parallelism
+vllm serve meta-llama/Llama-2-70b-hf \
+  --tensor-parallel-size 4 \
+  --gpu-memory-utilization 0.9 \
+  --quantization awq \
+  --port 8000
+
+# For production with caching and metrics
+vllm serve meta-llama/Llama-3-8B-Instruct \
+  --gpu-memory-utilization 0.9 \
+  --enable-prefix-caching \
+  --enable-metrics \
+  --metrics-port 9090 \
+  --port 8000 \
+  --host 0.0.0.0
+```
+
+**Step 2: Test with limited traffic**
+
+Run load test before production:
+
+```bash
+# Install load testing tool
+pip install locust
+
+# Create test_load.py with sample requests
+# Run: locust -f test_load.py --host http://localhost:8000
+```
+
+Verify TTFT (time to first token) < 500ms and throughput > 100 req/sec.
+
+**Step 3: Enable monitoring**
+
+vLLM exposes Prometheus metrics on port 9090:
+
+```bash
+curl http://localhost:9090/metrics | grep vllm
+```
+
+Key metrics to monitor:
+- `vllm:time_to_first_token_seconds` - Latency
+- `vllm:num_requests_running` - Active requests
+- `vllm:gpu_cache_usage_perc` - KV cache utilization
+
+**Step 4: Deploy to production**
+
+Use Docker for consistent deployment:
+
+```bash
+# Run vLLM in Docker
+docker run --gpus all -p 8000:8000 \
+  vllm/vllm-openai:latest \
+  --model meta-llama/Llama-3-8B-Instruct \
+  --gpu-memory-utilization 0.9 \
+  --enable-prefix-caching
+```
+
+**Step 5: Verify performance metrics**
+
+Check that deployment meets targets:
+- TTFT < 500ms (for short prompts)
+- Throughput > target req/sec
+- GPU utilization > 80%
+- No OOM errors in logs
+
+### Workflow 2: Offline batch inference
+
+For processing large datasets without server overhead.
+
+Copy this checklist:
+
+```
+Batch Processing:
+- [ ] Step 1: Prepare input data
+- [ ] Step 2: Configure LLM engine
+- [ ] Step 3: Run batch inference
+- [ ] Step 4: Process results
+```
+
+**Step 1: Prepare input data**
+
+```python
+# Load prompts from file
+prompts = []
+with open("prompts.txt") as f:
+    prompts = [line.strip() for line in f]
+
+print(f"Loaded {len(prompts)} prompts")
+```
+
+**Step 2: Configure LLM engine**
+
+```python
+from vllm import LLM, SamplingParams
+
+llm = LLM(
+    model="meta-llama/Llama-3-8B-Instruct",
+    tensor_parallel_size=2,  # Use 2 GPUs
+    gpu_memory_utilization=0.9,
+    max_model_len=4096
+)
+
+sampling = SamplingParams(
+    temperature=0.7,
+    top_p=0.95,
+    max_tokens=512,
+    stop=["</s>", "\n\n"]
+)
+```
+
+**Step 3: Run batch inference**
+
+vLLM automatically batches requests for efficiency:
+
+```python
+# Process all prompts in one call
+outputs = llm.generate(prompts, sampling)
+
+# vLLM handles batching internally
+# No need to manually chunk prompts
+```
+
+**Step 4: Process results**
+
+```python
+# Extract generated text
+results = []
+for output in outputs:
+    prompt = output.prompt
+    generated = output.outputs[0].text
+    results.append({
+        "prompt": prompt,
+        "generated": generated,
+        "tokens": len(output.outputs[0].token_ids)
+    })
+
+# Save to file
+import json
+with open("results.jsonl", "w") as f:
+    for result in results:
+        f.write(json.dumps(result) + "\n")
+
+print(f"Processed {len(results)} prompts")
+```
+
+### Workflow 3: Quantized model serving
+
+Fit large models in limited GPU memory.
+
+```
+Quantization Setup:
+- [ ] Step 1: Choose quantization method
+- [ ] Step 2: Find or create quantized model
+- [ ] Step 3: Launch with quantization flag
+- [ ] Step 4: Verify accuracy
+```
+
+**Step 1: Choose quantization method**
+
+- **AWQ**: Best for 70B models, minimal accuracy loss
+- **GPTQ**: Wide model support, good compression
+- **FP8**: Fastest on H100 GPUs
+
+**Step 2: Find or create quantized model**
+
+Use pre-quantized models from HuggingFace:
+
+```bash
+# Search for AWQ models
+# Example: TheBloke/Llama-2-70B-AWQ
+```
+
+**Step 3: Launch with quantization flag**
+
+```bash
+# Using pre-quantized model
+vllm serve TheBloke/Llama-2-70B-AWQ \
+  --quantization awq \
+  --tensor-parallel-size 1 \
+  --gpu-memory-utilization 0.95
+
+# Results: 70B model in ~40GB VRAM
+```
+
+**Step 4: Verify accuracy**
+
+Test outputs match expected quality:
+
+```python
+# Compare quantized vs non-quantized responses
+# Verify task-specific performance unchanged
+```
+
+## When to use vs alternatives
+
+**Use vLLM when:**
+- Deploying production LLM APIs (100+ req/sec)
+- Serving OpenAI-compatible endpoints
+- Limited GPU memory but need large models
+- Multi-user applications (chatbots, assistants)
+- Need low latency with high throughput
+
+**Use alternatives instead:**
+- **llama.cpp**: CPU/edge inference, single-user
+- **HuggingFace transformers**: Research, prototyping, one-off generation
+- **TensorRT-LLM**: NVIDIA-only, need absolute maximum performance
+- **Text-Generation-Inference**: Already in HuggingFace ecosystem
+
+## Common issues
+
+**Issue: Out of memory during model loading**
+
+Reduce memory usage:
+```bash
+vllm serve MODEL \
+  --gpu-memory-utilization 0.7 \
+  --max-model-len 4096
+```
+
+Or use quantization:
+```bash
+vllm serve MODEL --quantization awq
+```
+
+**Issue: Slow first token (TTFT > 1 second)**
+
+Enable prefix caching for repeated prompts:
+```bash
+vllm serve MODEL --enable-prefix-caching
+```
+
+For long prompts, enable chunked prefill:
+```bash
+vllm serve MODEL --enable-chunked-prefill
+```
+
+**Issue: Model not found error**
+
+Use `--trust-remote-code` for custom models:
+```bash
+vllm serve MODEL --trust-remote-code
+```
+
+**Issue: Low throughput (<50 req/sec)**
+
+Increase concurrent sequences:
+```bash
+vllm serve MODEL --max-num-seqs 512
+```
+
+Check GPU utilization with `nvidia-smi` - should be >80%.
+
+**Issue: Inference slower than expected**
+
+Verify tensor parallelism uses power of 2 GPUs:
+```bash
+vllm serve MODEL --tensor-parallel-size 4  # Not 3
+```
+
+Enable speculative decoding for faster generation:
+```bash
+vllm serve MODEL --speculative-model DRAFT_MODEL
+```
+
+## Advanced topics
+
+**Server deployment patterns**: See [references/server-deployment.md](references/server-deployment.md) for Docker, Kubernetes, and load balancing configurations.
+
+**Performance optimization**: See [references/optimization.md](references/optimization.md) for PagedAttention tuning, continuous batching details, and benchmark results.
+
+**Quantization guide**: See [references/quantization.md](references/quantization.md) for AWQ/GPTQ/FP8 setup, model preparation, and accuracy comparisons.
+
+**Troubleshooting**: See [references/troubleshooting.md](references/troubleshooting.md) for detailed error messages, debugging steps, and performance diagnostics.
+
+## Hardware requirements
+
+- **Small models (7B-13B)**: 1x A10 (24GB) or A100 (40GB)
+- **Medium models (30B-40B)**: 2x A100 (40GB) with tensor parallelism
+- **Large models (70B+)**: 4x A100 (40GB) or 2x A100 (80GB), use AWQ/GPTQ
+
+Supported platforms: NVIDIA (primary), AMD ROCm, Intel GPUs, TPUs
+
+## Resources
+
+- Official docs: https://docs.vllm.ai
+- GitHub: https://github.com/vllm-project/vllm
+- Paper: "Efficient Memory Management for Large Language Model Serving with PagedAttention" (SOSP 2023)
+- Community: https://discuss.vllm.ai
+
+
+