I have a box I recently updated to kernel 2.6.6-1.435 from 2.6.5-1.358. This box has no swap and 4GB of memory. Normally, when it runs, about 2.5GB of that memory is consumed by file cache. This is the desired behavior. After upgrading to 2.6.6-1.435, at least once every five minutes, kswapd runs and completely wipes out the file cache. It's not caching other information, it's just completely clearing it out so the box has about 2.5GB of memory free. This isn't desired, because then all the stuff that was cached needs to be re-cached, pegging I/O on the box and killing performance of our application.
What type of workload does your application produce?
Are you mounting and unmounting drives all of the time? That can show the behaviour you're describing... Maybe you don't want the automounter turned on on your server. Maybe you just need to set a longer timeout...
Mike
