Google

"You are writing a userspace storage driver to hit 10 million IOPS over NVMe-oF without kernel interrupt overhead": The interviewer challenged me to design an asynchronous submission path that eliminates context switching and system call jitter; I walked through an implementation using io_uring in IORING_SETUP_SQPOLL mode paired with zero-copy fixed memory buffers, using user-space polling over hugepages to bypass page-cache lock contention entirely. "An autonomous driving perception stack needs to reconcile 3D bounding boxes across asynchronous camera feeds and radar point clouds under sensor degradation": The panel asked how to track targets when heavy rainfall causes severe sensor dropouts; I formulated a Multi-Hypothesis Tracking (MHT) pipeline with track-to-track fusion using an Unscented Kalman Filter (UKF) to accommodate non-linear vehicle kinematics, resolving data association ambiguities across frames via the Murty algorithm for k-best bipartite assignments. "You need to implement an instruction scheduler inside a JIT compiler that reorders machine instructions for an out-of-order superscalar CPU": The interviewer asked how to maximize instruction-level parallelism (ILP) without exhausting architectural registers or stalling execution ports; I walked through constructing a directed acyclic dependency graph (DAG) of the basic block, then applied critical-path list scheduling weighted by functional unit latencies while maintaining a live-range threshold to prevent register pressure from forcing spill code.