I have an Ubuntu EC2 instance on amazon.
The instance has an apache2 webserver serving php5 code.
I'm using APC for op-code caching, Zend Framework as my framework, and Doctrine 2.2 as my ORM.
I know there are other bottlenecks, however I am asking specifically regarding the php files aspect.
I'm using memcache for db caching and configuration files caching (if any); I'm using a CDN for static files serving; And I'm well aware of the wait for external responses such as facebook api, etc..
Which filesystems are better for serving php code ?