This is a lesson learned from yesterdays fun at the Data center.
The IBM Http server and probably the Apache web server are sensitive to memory of the operating system regardless of the memory allocated to them.
We have been experiencing a problematic behavior from our webservers. they were slowing the application response time by 15-20 seconds and were generally running on high CPU cycles.
The system they were running on had 1Gb of memory allocated to it and we were sure this was sufficient since the JVM of the webserver was around 256Mb.
At some point we noticed a big amount of page faults on the Apache process and decided to get the memory increased.
We had installed on our servers 4Gb memory chips instead of the 1Gb and restarted the servers.
Accidentally we had hit the server prior to resetting its memory allocation and we were surprised that the response was less then a second.
Getting this response made us really happy and we decided to leave the memory as is and let it run that way.
Appearance there is an issue with the OS and the JVM stepping on each other heals in the Processing area and not the JVM area thus creating a slower processing from the Http server.
So next time you have a webserver with performance issues you might consider just putting some memory chips in it and see what it does.