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

*** 147,157 ****
          struct sysent *callp;
          struct sysent *se = LWP_GETSYSENT(lwp);
          int error = 0;
          uint_t nargs;
  
!         ASSERT(t == curthread && curthread->t_schedflag & TS_DONT_SWAP);
  
          lwp->lwp_ru.sysc++;
          lwp->lwp_eosys = NORMALRETURN;  /* assume this will be normal */
  
          /*
--- 147,157 ----
          struct sysent *callp;
          struct sysent *se = LWP_GETSYSENT(lwp);
          int error = 0;
          uint_t nargs;
  
!         ASSERT(t == curthread);
  
          lwp->lwp_ru.sysc++;
          lwp->lwp_eosys = NORMALRETURN;  /* assume this will be normal */
  
          /*
*** 241,252 ****
          proc_t *p = ttoproc(t);
          int     repost;
  
          t->t_pre_sys = repost = 0;      /* clear pre-syscall processing flag */
  
-         ASSERT(t->t_schedflag & TS_DONT_SWAP);
- 
  #if defined(DEBUG)
          /*
           * On the i386 kernel, lwp_ap points at the piece of the thread
           * stack that we copy the users arguments into.
           *
--- 241,250 ----