BCCE: Block-Centric GPU Co-Design for Real-Time Range-Top-K Query at Scale
Range-top-k queries retrieve the top-k elements within an arbitrary subrange of a large array and are a key primitive in real-time analytics. Unlike one-shot top-k selection, practical deployments issue large volumes of queries over varying and often overlapping ranges, frequently interleaved with streaming updates. In this setting, applying conventional GPU top-k kernels per query is inefficient: each query triggers range rescans or O(n)-scale passes that overwhelm HBM bandwidth, thrash on-chip caches, and provide little reuse across overlapping windows. We present BCCE, a GPU-co-designed, block-centric engine that makes range-top-k efficient by exposing a reusable intermediate representation of the data. BCCE partitions the array into locally sorted blocks and builds a compact interval-aware auxiliary index, reducing each query to a small set of contiguous active slices that remain amenable to SIMT execution. Queries are answered via a two-layer search: a global rank-thresholding step identifies the candidate value interval, followed by block-local verification restricted to the corresponding slices. This design constrains the active working set to \(O(\sqrt {n})\) and achieves \(O(\sqrt {n}\log n)\) per-query time with largely coalesced accesses and high on-chip reuse. To further improve throughput, BCCE employs a DP-based cache placement policy to keep hot slices resident in L2 or shared memory, and a range-grouped batching scheme that amortizes PCIe transfers for out-of-core datasets by reusing fetched slices across queries. Finally, BCCE supports incremental, block-local insertions and deletions without global rebuilds, sustaining performance under continuous data evolution. Across 17 datasets, including up to 70B elements (256 GB), BCCE achieves sub-millisecond query latency and up to 56, 308 × higher throughput than state-of-the-art GPU baselines, while performing billion-scale dynamic updates in milliseconds.