c6ba3edf9d
tripping over this getting too large, and suffering other performance problems due to the lack of good backpressure shrinking the bufcache when other memory is required. Again, this tunable should be revisited when the backpressure mechanism has been improved. sysctl vm.bufcache can be used to manually tune those rare machines that might need more than this. See comments in rev 1.106 for more detail.