Asynchronous I/O
Asynchronous I/O
- Subject: Asynchronous I/O
- From: Lamont Cranston <email@hidden>
- Date: Fri, 26 Mar 2004 13:08:04 -0800 (PST)
I'm developing a utility that measures AIO disk performance in 10.3.3. I'm using aio_read(), aio_write(), etc. If I do AIO to, say, two drives (rdisks) with a queue depth of 5, everything works fine. If I increase the queue depth to 10 (I didn't try anything in between), I start getting failures for aio_read and aio_write. errno = EAGAIN. I've determined that the copyin call is failing (result = 0x23) in the aio_queue_async_request call. I'm using one buffer for all reads and one for writes (the data is not important). Also, once I get this error, I continue to get it until I reboot - even if I just do one request to one drive.
What am I doing wrong or what are the system limitations? IMHO, 20 outstanding requests is not extravagant.
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