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Transformer Architecture and Attention Questions

Comprehensive understanding of Transformer architecture and attention mechanisms including the principles of self attention where queries keys and values are used to compute attention weights with appropriate scaling. Understand scaled dot product attention and multi head attention and why parallel attention heads improve representational capacity. Know positional encoding schemes including absolute positional encodings relative positional encodings rotary position encodings and alternative methods for injecting order information. Be able to explain encoder and decoder components feed forward networks residual connections and layer normalization and their role in training stability and optimization. Discuss attention variants and efficiency improvements such as sparse attention local windowed attention linear attention kernel based approximations and other methods to reduce memory and compute cost along with their trade offs. At senior and staff levels be prepared to reason about scaling Transformers to very large parameter counts including distributed training strategies parameter and data parallelism memory management and attention pattern design for long sequences and efficient inference. Be ready to apply this knowledge to sequence modeling language modeling and sequence transduction tasks and to justify architectural and implementation trade offs.

MediumTechnical
27 practiced
You visualize attention maps and see most heads in top layers attending heavily to a single EOS token regardless of input. Propose diagnostics to determine if this is a problem, possible root causes (data, objective, optimization), and corrective actions you would try in order.
MediumSystem Design
24 practiced
Design batching and padding strategies for training large Transformer models efficiently: discuss bucketing, dynamic padding, packing multiple short sequences into one batch entry, and interactions with mixed-precision and gradient accumulation. Provide a prioritized list of techniques to increase throughput while controlling memory.
HardSystem Design
25 practiced
Design a distributed training strategy to train a 100-billion parameter Transformer across a multi-node GPU cluster. Address model parallelism choices (tensor vs pipeline vs sequence parallelism), ZeRO optimizer-stage choices, memory balancing, gradient synchronization, checkpointing strategy, and expected communication bottlenecks.
EasyTechnical
23 practiced
Explain the purpose of masking in decoder self-attention for autoregressive models. Describe an efficient way to implement causal masking during training and during incremental inference (streaming decoding), and discuss the performance implications of each.
HardTechnical
31 practiced
Explain techniques to scale inference for very large models with low latency: tensor parallelism, pipeline parallelism, kernel fusion, quantization to INT8/4, offloading layers to CPU, and model-splitting across devices. For each, describe the main benefits, typical implementation complexity, and when you would prefer it in production.

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