First - all my servers are running fine. Thanks a ton to nginx! Lately, I have been brainstorming a lot on 3 configuration variables to squeeze maximum performance that I can get from my hardware.

[b]3 variables of my interest are:[/b]
[list=1]
[*] worker_processes
[*] worker_connections
[*] PHP_FCGI_CHILDREN
[/list]

I searched extensively on Google, mailing lists, wiki, etc but till date couldn't find any robust guide as on how these affects performance and other aspects of my webserver/webapp.

As I am aiming for very-very high traffic configuration, I will first move all images/js/css load to CDN.
So my nginx will be mostly busy in dealing PHP stuff.
[list]
[*] So will it make more sense to increase PHP_FCGI_CHILDREN or worker_processes?
[*] Is it good to make [i]PHP_FCGI_CHILDREN = 1[/i] if I am using APC for PHP opcode caching?
[/list]

If I want to achieve number of 100,000, then what is difference between following arithmetic:
[list]
[*] 10 worker_processes * 10,000 worker_connections * 1 PHP_FCGI_CHILDREN
[*] 10 worker_processes * 1,000 worker_connections * 10 PHP_FCGI_CHILDREN
[*] 10 worker_processes * 100 worker_connections * 100 PHP_FCGI_CHILDREN
[*] 1 worker_processes * 1000 worker_connections * 100 PHP_FCGI_CHILDREN
[*] 1 worker_processes * 100,000 worker_connections * 1 PHP_FCGI_CHILDREN
[/list]
I know this arithmetic is not straight-forward as 3 variable controls 3 different aspects. But how does they impact each other? How amount of RAM, traffic pattern, PHP/non-PHP traffic ratio affects them?

In short, what are all parameters I must consider?

Sorry if some of my questions sounds lame. But I really wants to dig deeper into nginx config for high traffic load.
Also if you think I am totally going in wrong direction, please feel free to correct me.

Thanks,
-Rahul

--
Rahul Bansal
EasyEngine - https://github.com/rtCamp/easyengine