Hi! > >> 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. > > I don't think so, since it's an implementation detail and subject to > change. That is for sure, but I would like to advice the user of the interface that nr_events is the maximum that could be expected to portably work. -- 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
