Technical practice
How would you design a distributed training toolchain for an ultra-large-scale model?
What to coverSuggested preparation: Explain the responsibilities of the training framework, distributed execution, monitoring, and data flow, using PyTorch, DeepSpeed, or Megatron-LM where relevant. Discuss how you would validate that the toolchain remains efficient and stable as it scales.
When is data parallelism a good choice, and what limits its scaling?
What to coverSuggested preparation: Cover gradient synchronization, memory demands, and communication overhead. Explain what measurements would tell you whether adding workers is improving useful training throughput.
How would you choose between pipeline and tensor parallelism for a large Transformer?
What to coverSuggested preparation: Compare partitioning, communication patterns, memory savings, and pipeline idle time. Explain how model size and available GPU resources would influence the choice.
What changes when training uses expert parallelism?
What to coverSuggested preparation: Discuss how routing and expert placement affect communication, load balance, and utilization. Describe how you would investigate uneven expert workloads without assuming a particular model design.
How would you locate a training bottleneck across computation, communication, and storage?
What to coverSuggested preparation: Describe the measurements you would collect at each layer and how you would distinguish a GPU compute limit from synchronization or data-delivery delays. Explain how you would verify that an optimization improves end-to-end training efficiency.
How would you debug training that becomes unstable as it scales?
What to coverSuggested preparation: Separate numerical or model-training symptoms from distributed-system failures and resource bottlenecks. Explain how controlled comparisons, logs, and targeted measurements would narrow the cause before a fix is rolled out.
When would you develop or debug a CUDA kernel for this training workload?
What to coverSuggested preparation: Relate GPU architecture and kernel behavior to a measured performance problem rather than optimizing speculatively. Discuss correctness checks, profiling, and the trade-off between a custom kernel and an existing operation.
How would you investigate an NCCL communication slowdown or a cuDNN-related performance issue?
What to coverSuggested preparation: Explain how you would isolate communication from GPU computation and compare behavior across workload sizes or configurations. Address both performance and correctness when testing a proposed change.
What considerations matter when scaling video pre-training with Transformers or diffusion models?
What to coverSuggested preparation: Connect video data and model architecture to memory use, computation, and distributed-training choices. Use Stable Diffusion or Flux only as examples of diffusion models named in the posting; avoid assuming the team uses a specific architecture.
How would you evaluate an emerging distributed-training technique before production implementation?
What to coverSuggested preparation: Propose a comparison against an existing approach using throughput, stability, scalability, and implementation cost. Explain how you would turn promising research into a staged, production-grade project plan.
Behavioural practice
Tell me about a time you resolved a difficult training-performance or stability problem.
What to coverSuggested preparation: Use a real situation, the evidence you gathered, and the actions you took to isolate the bottleneck. State the result with whatever measurements you actually have, including any remaining trade-offs.
Describe a time you collaborated across specialties on a complex technical project.
What to coverSuggested preparation: Set out the situation, your contribution, and how you coordinated decisions or resolved differing views. Explain the outcome and what the collaboration changed.
Tell me about a time you moved a promising technical idea toward a production-grade implementation.
What to coverSuggested preparation: Describe the initial idea, your evaluation and planning actions, and how you addressed implementation risks. Give the actual result without implying a deployment if one did not occur.
Describe a time you communicated a technical trade-off to people with different priorities.
What to coverSuggested preparation: Explain the situation, the options you presented, and how you made the evidence understandable. Describe the decision or next step and your role in reaching it.