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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.

MediumSystem Design
0 practiced
You're tasked with modeling documents longer than 2048 tokens. Propose architecture and system-level approaches to handle long-context modeling: local windows, strided windows, global tokens, compressed memory, retrieval augmentation, and trade-offs between compute, latency, and performance.
HardTechnical
0 practiced
A large Transformer training run shows sudden loss spikes and gradient explosions after warmup completes. Outline a systematic debugging and mitigation plan: what signals to inspect (per-layer gradients, weight norms, LR schedule), quick mitigations to stabilize training, and long-term fixes to prevent recurrence.
HardSystem Design
0 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.
MediumSystem Design
0 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.
MediumTechnical
0 practiced
Estimate the memory footprint of a single Transformer attention layer during forward and backward pass. Given sequence length L, head count H, head dim d_h, and batch size B, include activations, attention logits, gradients, and optimizer states. Explain where the O(L^2) term arises and how activation memory dominates at large L.

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