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

@@ -4320,18 +4320,10 @@
 
         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;