POSIX_FADV_VOLATILE

I believe that the kernel should reclaim the entire range, however I also think that a big application would have several levels of cache and in the case of tabs each tab might have a cache.

I don't know what effect having many small POSIX_FADV_VOLATILE ranges would be, but an application could clearly make decisions that would pool small caches into one bigger in order to keep the total number of POSIX_FADV_VOLATILE ranges reasonable.

Perhaps exposing the average lifetime over the past five minuets of any POSIX_FADV_VOLATILE range would help an application decide if it should even bother. There can be other performance counters that would help an application determine the number and target size of
POSIX_FADV_VOLATILE ranges.