Implement a sliding window for VF cache invalidates?
We seem to hit piles of VF cache invalidates due to having buffers in two 4GB ranges. But, they tend to be at the bottom of one range and top of the next - which means that they don't actually have a 32-bit cache key truncation problem.
Jason suggested instead tracking a range of data in the VF cache, and if it ever grows to more than 4GB in length, do a VF invalidate. This would probably eliminate most VF flushes.