Re: [PATCH 0/7] Non-blocking AIO

Re: [PATCH 0/7] Non-blocking AIO

[Michael Kerrisk]

[CC += linux-api]

Hello Goldwyn,

Since this is a kernel-user-space API change, please CC linux-api@
(and for future iterations of this patch series).

The kernel source file Documentation/SubmitChecklist notes that all
Linux kernel patches that change userspace interfaces should be CCed
to linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, so that the various parties who are
interested in API changes are informed. For further information, see
https://www.kernel.org/doc/man-pages/linux-api-ml.html

Cheers,

Michael



On Tue, Feb 14, 2017 at 3:45 AM, Goldwyn Rodrigues <rgoldwyn-l3A5Bk7waGM@public.gmane.org> wrote:
> This series adds nonblocking feature to asynchronous I/O writes.
> io_submit() can be delayed because of a number of reason:
>  - Block allocation for files
>  - Data writebacks for direct I/O
>  - Sleeping because of waiting to acquire i_rwsem
>  - Congested block device
>
> The goal of the patch series is to return -EAGAIN/-EWOULDBLOCK if
> any of these conditions are met. This way userspace can push most
> of the write()s to the kernel to the best of its ability to complete
> and if it returns -EAGAIN, can defer it to another thread.
>
> In order to enable this, IOCB_FLAG_NONBLOCKING is introduced in
> uapi/linux/aio_abi.h which translates to IOCB_BLOCKING for struct iocb.
>
> This feature is provided for direct I/O of asynchronous I/O only. I have
> tested it against xfs, ext4, and btrfs.
>
> --
> Goldwyn
>
>



-- 
Michael Kerrisk Linux man-pages maintainer;
http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface", http://blog.man7.org/