Background: I maintain a server for a client who has half a dozen Wordpress sites on. They all have the W3 Total Cache plugin installed and eAcellerator is installed (might be APC).
All the PHP sites run through a single batch of fastcgi php-cgi processes (it's actually php-fpm but I'm not sure if that makes a difference) and that feeds into nginx.
Problem: php-cgi's CPU usage is quite high. Not terminally high but high enough to raise an eyebrow. The client wants to add more sites in the future and I want to avoid becoming CPU limited if I can help it.
Question: Is there any way I can find the scripts or even just requests that are causing the high CPU. I realise I might not be able to do anything with the results but it would give me a chance.