> hm, in that case, wouldn't adding 48gb of physical memory have
> approximately the same effect? or is something else going on?
imho, adding 48gb would have no effects.
server already has 376GB memory and still has a lot of unused GB.
let me repeat, we added 80GB for files cache by decreasing buffers from 64GB to 16GB.
there are was 150GB of unused, and now unused part is only 70GB.
some of links i read about eviction
http://linux-mm.org/PageReplacementDesign
http://linux-mm.org/PageReplacementRequirements
mikhail