Hi! > > Looking carefully at the io_setup.2 man page it says: > > > > ... > > The io_setup() system call creates an asynchronous I/O context capable > > of concurrently processing at least nr_events. > > ... > > ^ > > The 'at least' caught my eye, as it is it > > may suggest that the nr_events is low limit > > on the number of events. > > > > > > Wouldn't be 'at most' more appropriate here? Quick look in the kernel > > sources suggest that it allocates buffers for nr_events elements. > > > > Or am I missing something? > > When the kernel ring buffer is setup, it is created in page size > chunks, and nr_events is rounded up: > > /* Compensate for the ring buffer's head/tail overlap entry */ > nr_events += 2; /* 1 is required, 2 for good luck */ > > size = sizeof(struct aio_ring); > size += sizeof(struct io_event) * nr_events; > nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; > > if (nr_pages < 0) > return -EINVAL; > > nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); Ah, now it all makes sense. And I'm thinking if it is worth of adding more clear description. -- Cyril Hrubis chrubis@xxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
