zfs primarycache and secondarycache properties [PSARC/2008/393 FastTrack timeout 06/27/2008]

[Bill Sommerfeld]

Does setting these properties to a more-restrictive setting drop
now-excluded cache entries immediately?  (in other words, would setting
primarycache=none and then setting it back to all serve to empty the
cache of any entries from the affected datasets, and free up the
corresponding system memory or cache disk space?)