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JohnScheuer/README.md

João Felipe De Souza

AI Systems Engineer | LLM Infrastructure & GPU Optimization

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Building high-performance foundations for Next-Gen AI. Expert in squeezing maximum TFLOPS out of consumer hardware and scaling LLM inference across distributed clusters.

Currently based in Curitiba, Brazil (GMT-3). Open to relocation worldwide.


🚀 Flagship Infrastructure Projects

⚡ mini-llm-inference-engine

Full C++/CUDA Runtime

  • Transformer inference engine in pure C++/CUDA, no PyTorch execution path.
  • 32.4k tok/s peak, achieving 87% of INT8 Tensor Core ceiling on RTX 2070.
  • Custom Flash Attention, cuBLASLt INT8, CUDA Graphs, Megatron-style TP.
  • Runs TinyStories 110M and TinyLlama 1.1B end-to-end.

⚡ sm75-tensorcore-microkernel

PTX-Level GEMM Engineering

  • Manual PTX instruction emission for Tensor Core GEMM.
  • Beats cuBLAS at 2048×2048×2048; achieves 60-65% at 8192×8192×8192.
  • Auto-tuning over WARPS / STAGE_K / ILP_DEPTH configuration space.

⚡ fused-int4-gemm-sm75

CUDA Kernel + End-to-End LLM Integration

  • Bit-perfect INT4 weight-only quantization kernel using raw PTX assembly.
  • Achieved 1.000 Cosine Similarity against FP16 baselines.
  • End-to-end Qwen2-0.5B integration: -14.7% VRAM with coherent output.
  • Documented SM75 structural limits (no cp.async, no INT4 MMA operands).

🏗️ llm-fusion-compiler

Compiler MVP with CUDA Codegen

  • Full pipeline: IR → CUDA codegen → nvcc → GPU execution.
  • 9 Transformer fusion patterns (GEMM+Bias+GeLU, LayerNorm fusion, etc.).
  • 10.5 TFLOPS peak on RTX 2070 (37% of SM75 theoretical peak).
  • Templated CUDA generation via Jinja2 with type/shape specialization.

🌐 distributed-inference-engine

LLM Scaling & Distributed Systems

  • Multi-process runtime implementing Megatron-style Tensor Parallelism and Pipeline Parallelism.
  • GPipe Scheduler: Fill-drain micro-batching to minimize idle bubbles.
  • KV Cache Sharding: Distributed attention state to scale beyond single-GPU VRAM limits.
  • Bit-identical validation on Qwen2-0.5B weights.

🛠️ custom-llm-serving-engine

Production Serving Runtime

  • OpenAI-compatible inference server (/v1/completions, /v1/chat/completions).
  • Continuous batching, SSE streaming, KV cache management.
  • Prometheus metrics, graceful shutdown, health checks.
  • 33/33 unit tests + 6/6 end-to-end scenarios passing.

🌍 llm-gateway-saas

LLM-as-a-Service Platform (Production-Ready)

  • High-concurrency backend with OpenAI-compatible API.
  • ACID Billing: PostgreSQL-backed financial ledger with Decimal precision.
  • Distributed Rate Limiting: Redis ZSET sliding window (multi-worker safe).
  • Tool calling execution layer, Stripe integration, admin dashboard.
  • Production stack: Docker Compose, Gunicorn, Prometheus.

📉 quantization-runtime

Mathematical Model Compression

  • From-scratch implementation of AWQ and GPTQ algorithms.
  • Validated intelligence preservation on Qwen2-0.5B with 26.05 Perplexity at 4-bit.
  • Deep-dive study on Hessian-based error compensation vs activation salience.

🧪 R&D & Specialized Runtimes

  • flash-attention-sm75-register-fused: Register-fused FlashAttention for Turing (5.0 TFLOPS peak, roofline-validated).
  • flash-attention-sm75: FlashAttention v1 forward pass in CUDA for SM75.
  • fused-backward-kernels-sm75: Fused GEMM+Bias+GeLU backward kernels (3.1× faster than autograd at M=1024).
  • rag-inference-stack: High-speed local RAG using ChromaDB and sentence-transformers.
  • speculative-decoding-runtime: Accelerated inference (1.41× speedup) via draft-model verification.
  • vlm-inference-runtime: Multi-modal deployment wrapper for Vision-Language Models.
  • lora-inference-runtime: Multi-tenant serving with sub-3ms adapter hot-swapping.

🛠️ Technical Arsenal

Layer Technologies
Silicon & Hardware CUDA C++, PTX Assembly, Tensor Cores (WMMA), CUDA Graphs, Nsight Compute
Compilers & Codegen IR design, CUDA codegen (Jinja2), MLIR/LLVM (studied), TVM concepts
AI Frameworks PyTorch, HuggingFace Transformers, PEFT, Tokenizers, ONNX
Distributed & Infra NCCL/Gloo, torch.distributed, Tensor Parallelism, Pipeline Parallelism
Serving & Runtime FastAPI, Continuous Batching, KV Cache Management, SSE Streaming
Backend & Scaling Redis (ZSET Rate Limiting), PostgreSQL (ACID), ChromaDB, Prometheus
DevOps Docker Compose, Gunicorn, Nginx, GitHub Actions
Languages C, C++ (17/20), CUDA, PTX, Python, Rust, TypeScript (basic)

🔬 Key Metrics Across Portfolio

Achievement Project
32.4k tok/s peak throughput mini-llm-inference-engine
87% INT8 Tensor Core ceiling mini-llm-inference-engine
10.5 TFLOPS compiler-generated llm-fusion-compiler
Beats cuBLAS at 2048² GEMM sm75-tensorcore-microkernel
1.000 Cosine Similarity INT4 vs FP16 fused-int4-gemm-sm75
Bit-identical distributed TP distributed-inference-engine
1.41× speedup speculative decoding speculative-decoding-runtime
26.05 PPL 4-bit AWQ quantization-runtime
R² = 0.9996 comm cost model comm-cost-modeling

💼 Experience

AI Infrastructure Engineer (Contract) — Confidential Leading Chinese LLM Company (Under NDA) | Sep 2025 – Mar 2026
Built Rust-based ingestion pipelines with Tokio async and backpressure-safe systems supporting an in-production LLM stack.

Software Architecture Lead & Operations Manager — ZBrasil (Cross-border E-commerce) | Apr 2025 – Aug 2025
Led backend architecture and GPU infrastructure decisions.


🌟 Open Source


📬 Connect & Collaborate


Code the math, scale the intelligence.

Pinned Loading

  1. mini-llm-inference-engine mini-llm-inference-engine Public

    High-performance Transformer inference engine in C++/CUDA — 32k tok/s peak, 87% INT8 Tensor Core ceiling, roofline-validated on RTX 2070

    C++ 9 1

  2. sm75-tensorcore-microkernel sm75-tensorcore-microkernel Public

    Instruction-level Tensor Core micro-kernel engineering on SM75 (RTX 2070), including PTX manual emission, shared-memory staging, and hardware-aware auto-tuning.

    Cuda

  3. llm-fusion-compiler llm-fusion-compiler Public

    Compiler MVP that detects Transformer fusion patterns, generates optimized CUDA kernels with WMMA Tensor Cores, and executes them on real GPU hardware — 10.5 TFLOPs on RTX 2070, correctness validat…

    Python 2

  4. custom-llm-serving-engine custom-llm-serving-engine Public

    Production-oriented LLM inference server with OpenAI-compatible API (/v1/completions, /v1/chat/completions). Continuous batching, SSE streaming, KV cache management, Prometheus metrics, and gracefu…

    Python 1

  5. distributed-inference-engine distributed-inference-engine Public

    Simulated Multi-GPU inference engine implementing Megatron-style Tensor Parallelism, GPipe Pipeline Parallelism, and KV Cache Sharding from scratch. Features bit-identical fidelity validation on Qw…

    Python

  6. fused-int4-gemm-sm75 fused-int4-gemm-sm75 Public

    Custom PTX INT4 GEMM kernel with Tensor Cores (WMMA) and end-to-end Qwen2 integration on NVIDIA Turing (SM75). Register-level dequantization, mma.sync.aligned intrinsics, and automatic M-padding wr…

    Python