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RadixArkPosted 3 weeks ago

Member of Technical Staff — Accelerator Systems

On-sitePalo Alto, California, United States

Full TimeSenior LevelStartup

Job Summary

Bring up RadixArk's inference and training systems on new accelerator platforms and drive them to competitive performance. Design hardware abstractions that let a single codebase stay fast across vendors without forking, and port and optimize kernels across programming models and memory architectures. Build cross-platform benchmarking, profiling, and regression detection so performance claims hold up on every target, while debugging numerical divergence and correctness gaps between platforms. Work with vendor engineering teams on pre-release hardware, compiler and driver issues, and roadmap feedback to serve as the internal source of truth on platform capabilities. Contribute hardware-specific optimizations, benchmarks, and portability work back to open-source SGLang and Miles.

Required Qualifications

  • 4+ years of experience in systems, performance, or ML infrastructure engineering
  • Deep expertise in at least one accelerator programming model (CUDA, ROCm/HIP, Pallas/XLA, Triton, or a vendor SDK), with demonstrated ability to pick up new ones quickly
  • Strong understanding of accelerator architecture: memory hierarchy, bandwidth limits, occupancy, and the tradeoffs between them
  • Experience writing or optimizing high-performance kernels for ML workloads
  • Experience with distributed execution and communication libraries (NCCL, RCCL, MPI, or equivalents)
  • Proficiency in C++ and Python
  • Strong debugging and profiling skills at the system level, including on platforms where the tooling is incomplete or unreliable
  • Track record of performance work that shipped into production

Desired Qualifications

  • Experience bringing up ML workloads on new silicon
  • Hands-on depth in more than one vendor ecosystem
  • Experience with compiler stacks (XLA, MLIR, TVM, Triton) or building compiler passes and IR transformations
  • Experience designing hardware abstraction layers or portable kernel interfaces
  • Quantization and mixed-precision work across differing numeric formats and hardware support levels
  • Experience with distributed inference systems (SGLang, vLLM) or training/RL frameworks (Miles, Megatron, veRL, TorchTitan)
  • CPU inference optimization (AVX-512/AMX, oneDNN, NUMA-aware execution)
  • Experience optimizing collective communication at scale, or scaling workloads to 1000+ accelerators
  • Contributions to kernel, compiler, or ML systems open source
  • Direct collaboration with silicon vendors or cloud partners on technical evaluations
  • Background in HPC or other performance-critical systems

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