Hello!

On Tue, Sep 06, 2011 at 01:21:00AM +0300, Hagai Avrahami wrote:

> Hi
>
> I configured Nginx with *aio *mode *on *and 1 *worker process*
> In benchmarking I saw limit of 1024 concurrent sessions even configured to
> 4096 *worker connections*

Sure it's not limitation of the benchmarking tool you use? Most
tools out there use select() and hence limited to 1024
concurrent connections.

> When I looked in the source code I could see that io_setup is called with
> fix value of 1024 max events
> can anyone please explain me the hard coded limit
> Is it OK to change it or it is derived from other limit I am not aware of
> any help will be appreciated

io_setup() maxevents is a limit on number of aio requests allowed
to be submitted simulteneously; if nginx hits this limit, it will
fallback to normal blocking read.

If you are going to change it, make sure to keep total for all
processes lower than /proc/sys/fs/aio-max-nr.

Maxim Dounin

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