Nginx + PHP 5.3.3 (with php-fpm) - memory usage?

I recently bought Xen VPS (linode.com) with Debian 5.0 Lenny (i386), 512MB RAM. At the moment I have only three small websites (built with Drupal) with about 600 users per day in total running on this server.

As a web server I use nginx 0.7.67 (PHP 5.3.3 with php-fpm). An average memory consumption is about 100-105MB. Here is what Munin graph shows:

and this is what "top" command diplays (sorted by memory usage):

In my php5-fpm.conf:

pm = dynamic
pm.max_children = 50
pm.start_servers = 2
pm.min_spare_servers = 2
pm.max_spare_servers = 5
pm.max_requests = 500

Before migrating some bigger projects to this VPS I'd like to know if this is a normal memory consumtion for this kind of server configuration? How many users on the website (let's say, built with Zend Framework) this VPS can handle?

Thank you!

From serverfault

• For me that looks good. Your PHP + MySQL is taking only around 100 megabytes of RAM, leaving lots of room for the operating system to breathe.

  For your "how many users this VPS can handle?" question: it depends. With proper caching and other best practices I think it should handle at least dozens of requests per second, if not more.

  If the content is highly dynamic and not very well cacheable and the database structure happens to be complex and/or the database is big, then the performance will suffer.

  Usually the memory will be the first limit you'll hit whenever your traffic grows, with highly dynamic content the CPU will be tortured, too.

  From Janne Pikkarainen