🤖 AI Summary
研究解决了Oracle数据库中高效I/O处理的问题，通过集成io_uring并采用混合存储I/O架构，在特定工作负载下降低了CPU利用率和提高了吞吐量。
📝 Abstract
We describe the integration of io_uring into Oracle Database's storage layer and the architectural decisions required to deploy it in a production multi-process RDBMS. Our design uses per-process ring contexts that eliminate inter-process synchronization, a shared buffer registration mechanism now part of the mainline Linux kernel, and a transparent fallback to libaio on error. Evaluation on an internal development build of Oracle Database 26ai shows that io_uring's benefits concentrate on asynchronous batched I/O paths: on a mixed OLTP workload (TPC-C), io_uring delivers identical throughput while reducing server CPU utilization by 1.2 percentage points through more efficient background writes; on analytical queries (TPC-H), CPU per query drops by 8.5% (geometric mean). Isolating the write path alone shows 29% lower CPU per write and 34% higher throughput. Synchronous read paths -- the dominant I/O in OLTP -- show no improvement and even increased CPU usage for very large I/O sizes. These results motivate a hybrid I/O architecture that retains pread/pwrite for synchronous operations, adopts io_uring for asynchronous batched I/O, and falls back transparently to libaio -- a selective strategy that may also be relevant to other database systems facing the same integration question.