Andrew's Blog

A tool I discovered: apachetop can read apache log files, and show performance data in a human readable format. apachetop will use the default apache log files, and apachetop -f /path/to/logfile will show stats for a selected log file.
Many hosts are configured using virtual hosts, and logging is done to separate log files for each virtual hosts. If this is the case, for performance debugging, it is a good idea to add a second log entry into the global log file. You can run as many CustomLog entries as you like.

CustomLog /var/log/httpd/customer_virtual_host-access_log combined
CustomLog logs/access_log combined

I have not looked to far into apachetop, but you can see the requests, requests per second, KB, KB/s and url of the file by default. There are more options, such as sort by, referers, and more and you can see these by pressing the “h” or “?” keys.
For some more info:
http://www.howtogeek.com/howto/ubuntu/monitor-your-website-in-real-time-with-apachetop/