Most administrators know that PHP, the widely used scripting language, can be embedded in HTML and works with all major web servers. What’s less widely known, however is that you can run PHP in different ways on your server. The most common option is the mod_php module that’s runs by default in the Apache HTTP Server. If your primarily goal is performance, however, you should consider other options. PHP-FPM (FastCGI Process Manager) and PHP FastCGI each have pros and cons, but either can speed up the performance of your PHP.
mod_php
Let’s start by looking at running Apache with mod_php. This package is present in just about every Linux distribution’s repository, so installing it is easy, and so is configuring and managing the software. In fact, its ease of use may be the main reason to deploy mod_php.
With mod_php the PHP interpreter is “embedded” inside the Apache process; Apache doesn’t call any external PHP process, which means that Apache and PHP can communicate better. However, every single Apache child must load mod_php, which results in a bigger process than necessary being used for serving static resources such as image files, CSS, and JavaScript.
Another problem with this method is that it works only on Apache. This is not always an issue, as Apache is the most complete web server you can find, but websites that run on small virtual private servers (VPS), or big sites that have to serve million of pages a day, might want a different web server that can scale up or down better than Apache, and would therefore need a different way to run PHP too.
Pros:
- Easy to install and update.
- Easy to configure with Apache.
Cons:
- Works only with Apache.
- Forces every Apache child to use more memory.
- Needs a restart of Apache to read an updated php.ini file.