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

*** 489,499 ****
  
          ASSERT_STACK_ALIGNED();
  
          type = rp->r_trapno;
          CPU_STATS_ADDQ(CPU, sys, trap, 1);
-         ASSERT(ct->t_schedflag & TS_DONT_SWAP);
  
          if (type == T_PGFLT) {
  
                  errcode = rp->r_err;
                  if (errcode & PF_ERR_WRITE)
--- 489,498 ----