I have successfully booted a kernel with it.
A pair of 'make buildworld' tests counted function calls and cycles spent on vm_radix_insert.
old
vm.radix.ins_cycles: 80079998931
vm.radix.ins_calls: 344880306
cycles/call: 232.19649698118744
Peter, can you test this please?
new
vm.radix.ins_cycles: 78438877181
vm.radix.ins_calls: 344817853
cycles/call: 227.47916472004715