"aio on" is unsupported on this platform

Hello!

I am attempting to enable asynchronous I/O for my NGINX server but I get the following error:

> sudo nginx -t -c /etc/nginx/nginx.conf
[emerg] "aio on" is unsupported on this platform in /etc/nginx/nginx.conf:33
nginx: configuration file /etc/nginx/nginx.conf test failed

I was under the impression that aio was supported (and async automatically turned on) for my distro/kernel:

> uname -a
Linux arch 3.19.3-3-ARCH #1 SMP PREEMPT Wed Apr 8 14:10:00 CEST 2015 x86_64 GNU/Linux

None of the articles I found showed a way to check if async was active on Arch Linux (/sys/slabinfo does not contain any "kio" entries). I tried to explicitly enable async in my /etc/fstab to no avail.

> pacman -Q libaio
libaio 0.3.110-1

Am I missing something here?

Thanks!