I have a small, though not tiny, VPS: 1.5GHz, 1GB dedicated RAM, 1GB burstable RAM, some 40GB HDD.
The stack is CentOS nginX mySQL(Percona) PHP-FPM.
I have 3 low traffic websites (10-40 visitors a day per site) each running a separate instance of WordPress.
Additionally, I have 3 more instances of WordPress. These 3 sites aren't launched yet, so effectively traffic is zero.
The CPU usage has never gone north of 5% in the last month or so.
Yet, PHP-FPM process is taking up a ton of memory. At the moment, I am using 3GB (don't know how...because dedicated+burstable available to me should only be 2GB).
PHP-FPM process for the 3 active websites are using 732MB, 438MB and 89MB respectively.
PHP-FPM process for the 4 zero-traffic, zero-content websites are using 679MB, 621MB, and 596MB respectively.
- php-fpm (apache) 127MB
- mysqld 122MB
- nginx 44MB
- named 21MB
- miniserv.pl 20MB
- lfd 16MB
- php-fpm (ispconfig) 13MB
- php-fpm (ispapps) 13MB
- php-fpm (root) 7MB
- newrelic-daemon 7MB
- nginx(root) 4MB
- rsyslogd(root) 3MB
- nrsysmond(newrelic) 3MB
- mysqld_safe(root) 2MB
Sample PHP-FPM config: http://hennalap.com/phpinfo.php