remove whole-process swapping
Long before Unix supported paging, it used process swapping to reclaim
memory.  The code is there and in theory it runs when we get *extremely* low
on memory.  In practice, it never runs since the definition of low-on-memory
is antiquated. (XXX: define what antiquated means)
You can check the number of swapout/swapin events with kstats:
$ kstat -p ::vm:swapin ::vm:swapout

*** 4320,4337 ****
  
          if (t->t_stkbase == NULL)
                  return (WALK_NEXT);
  
          /*
-          * Warn about swapped out threads, but drive on anyway
-          */
-         if (!(t->t_schedflag & TS_LOAD)) {
-                 mdb_warn("thread %p's stack swapped out\n", addr);
-                 return (WALK_NEXT);
-         }
- 
-         /*
           * Search the thread's stack for the given pointer.  Note that it would
           * be more efficient to follow ::kgrep's lead and read in page-sized
           * chunks, but this routine is already fast and simple.
           */
          for (current = (uintptr_t)t->t_stkbase; current < (uintptr_t)t->t_stk;
--- 4320,4329 ----