Missing Manuals - io_uring worker pool

The io_uring API is designed to provide a more efficient way for applications to handle I/O operations by allowing them to submit multiple requests in one go and then wait for all of them to complete, rather than having to make separate system calls for each request. This can help reduce the overhead associated with making these system calls and improve overall application performance. One important aspect of using io_uring is managing the worker pool size, which determines how many threads will be created to handle the submitted I/O requests. In this article, we explored different methods for setting this limit: 1. Using the IORING_REGISTER_IOWQ_MAX_WORKERS command when registering an IO work queue (io_wq). 2. Setting the RLIMIT_NPROC resource limit using the prlimit utility or by modifying /etc/security/limits.conf file. 3. Limiting the number of tasks within a control group using cgroups. 4. Using multiple instances of io_uring in single-threaded and multi-threaded programs, which can lead to different worker pool sizes depending on how many threads are operating on each instance. 5. Considering NUMA architecture when configuring the worker pool size, as it may affect the number of workers per NUMA node. By understanding these methods and their implications, developers can better optimize their applications' use of io_uring to achieve maximum performance benefits.