[PATCH] Add io_uring support in AIO(async io) module

[Mathew Heard]

If there are performance regressions perhaps these could be documented
in the events documentation. Something along the lines of a
recommended minimum kernel.

On Thu, 26 Aug 2021 at 11:48, Zhao, Ping <ping.zhao at intel.com> wrote:
>
> Hi Maxim,
>
> It's been long time and I lost the mail thread. Is it now the good time to return to io_uring? I saw kernel group made many progress on it. How does Nginx forum think about this new kernel feature?
>
> Best,
> Ping
>
> -----Original Message-----
> From: nginx-devel <nginx-devel-bounces at nginx.org> On Behalf Of Maxim Dounin
> Sent: March 22, 2021 12:18PM
> To: nginx-devel at nginx.org
> Subject: Re: [PATCH] Add io_uring support in AIO(async io) module
>
> Hello!
>
> On Sat, Feb 27, 2021 at 12:48:04PM +0000, Zhao, Ping wrote:
>
> > Yes, io_uring can help Nginx achieve same performance with lower
> > resource cost. This is the key improvement of io_uring I think.
> > It can't break through the HW limitation.
>
> Thanks for the patch and testing.
>
> Potentially this looks interesting, despite the fact that
> improvements even in terms of resource costs seem to be minor
> compared to properly configured nginx using other I/O variants.
>
> There are, however, some concerns regarding the interface itself
> and tunings need to be applied in order for it to work, as well
> as regressions in various kernels out there. There are also some
> questions about the patch, notably retries in case of short reads,
> though this probably needs better understanding of the interface.
>
> As of now, the consensus is that we'll get back to this some time
> later, though probably we want to make this not a default aio
> method at first, but rather an alternative one, available with
> something like "aio io_uring;", similarly to "aio threads;".
>
> Thanks again for your work. We'll contact you once we return to
> this topic.
>
> --
> Maxim Dounin
> http://mdounin.ru/
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