Microsoft

"You are designing an in-memory transactional processing engine that must achieve millions of commits per second on a single multi-socket machine without a central lock manager": The interviewer asked how to prevent memory bus saturation and transactional abort cascades under high write skew; I walked through implementing Silo's epoch-based optimistic concurrency control (OCC), detailing how local write-sets avoid shared cache-line invalidations, transaction IDs encode global epochs with lock bits, and centralized epoch advancement happens off the critical path using read-copy update (RCU) quiescence. "An automated driving platform requires an on-chip Network-on-Chip (NoC) interconnect that guarantees bounded delivery latency for safety-critical camera frames mixed with bursty sensor telemetry": The panel asked how to prevent head-of-line blocking and buffer starvation across mesh router nodes; I detailed a virtual-channel router architecture featuring credit-based flow control, dynamic flit deflection (hot-potato routing) as a deadlock-recovery escape mechanism, and strict Quality of Service (QoS) arbitration using deficit round-robin (DRR) to prioritize ISO 26262 ASIL-D packets over best-effort diagnostic traffic. "Design the instruction cache prefetcher for an out-of-order processor executing massive, disjoint server binaries with instruction footprints exceeding the L2 cache": The interviewer pointed out that spatial stream prefetchers fail catastrophically on non-contiguous call/return branches and indirect function pointers; I walked through the implementation of a Temporal Instruction Fetch Streaming (TIFS) or Proactive Instruction Fetch (PIF) engine, explaining how retirement-order commit traces are compressed into an off-chip or dedicated SRAM history buffer to replay discontinuous instruction fetch streams well ahead of pipeline fetch stages.