2.6.6-1.435: kswapd clears out cache?

[Philip Molter]

> 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...

No.

I actually also filed the same bug over at bugzilla.kernel.org and 
Andrew Morton informs me that it has to do with the SMP/NUMA code and 
the 4G/4G boundary.  By passing a mem=3936MB option to the kernel at 
boot time, the problem with the filesystem cache getting wiped out goes 
away.

Bug #2973 if anyone's interested in his explanation (which I don't do 
justice since I'm not a kernel VM coder).

Philip