How to optimize the php process memory usage?

Question

I am running a wordpress site and each PHP process usage about 200mb to 250mb resident size memory. With 16GB of ram, the server can only handle about 70 processes. By incre

Answer 1

Rasmus Lerdorf did a conference about PHP performance at Confoo in 2010 and he used a Wordpress blog as an example, this should give you great tools to answer your question:

http://talks.php.net/show/confoo10/1

To sum up:

• Run a phpinfo() and disable PHP extensions that you don't use. They can take a lot of memory (imagick, curl, ...)
• Generate a graph of your includes using the inclued.so extension. You might load useless functions in your wordpress setup.
• Run benchmarks with siege. Sometimes, tiny optimisations have great impact on performance, so make sure you have metrics, to help you make your decisions.
• Use callgrind to show where you're loosing performance. In one of my project I was using md5() to hash my SQL queries and cache them. The md5() calls where using 20% of the CPU time.

I would definitely start by disabling PHP extensions if possible.