Let's say I want to wait on a particular `vm_page_t'.  The `vm_page_t'
   needs to contain a `condvar_t'.  Or more precisely *every* `vm_page_t' in
   the system needs to contain a `condvar_t' even if it's only used in one
   piece of code.  If you have 1 byte `condvar_t' and 1000 pages of RAM
   that's 1K.  If the `condvar_t' is a pointer in LP64 that's 8K.  (Ignoring
   structure alignment and packing issues that may waste more space.)


let me just say that bloating vm_page some more is simply a bad idea
and should be rejected...  it is too large, already.