Optimizing Nginx for serving 1GB files - Finding values for 'directio' & 'output_buffers' (no replies)

Hi,

We have a Nginx web server which is serving files whose size is almost 1GB. We were trying to optimize the configuration with directio & output_buffers directives. but, we couldn't find any calculation/formula with which we can identify suitable values for above mentioned directives.

Server Spec

Processor: Intel E5-2600 Xeon Family (2cpus,16 cores each)
RAM: 32GB

Nginx config

Nginx Version: 1.3.9 (dev)
worker_processes 33;
worker_connections 1024;
use epoll;
worker_rlimit_nofile 33792;
aio on;
Could you plz explain how we can find values for 'directio' & 'output_buffers' specific to a server.

Thanks
Jayaraj