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

*** 29,40 ****
  /*
   * Portions of this source code were derived from Berkeley 4.3 BSD
   * under license from the Regents of the University of California.
   */
  
- #pragma ident   "%Z%%M% %I%     %E% SMI"
- 
  /*
   * VM - segment for non-faulting loads.
   */
  
  #include <sys/types.h>
--- 29,38 ----
*** 95,105 ****
          (faultcode_t (*)(struct seg *, caddr_t))
                  segnf_nomap,            /* faulta */
          segnf_setprot,
          segnf_checkprot,
          (int (*)())segnf_badop,         /* kluster */
-         (size_t (*)(struct seg *))NULL, /* swapout */
          (int (*)(struct seg *, caddr_t, size_t, int, uint_t))
                  segnf_nop,              /* sync */
          (size_t (*)(struct seg *, caddr_t, size_t, char *))
                  segnf_nop,              /* incore */
          (int (*)(struct seg *, caddr_t, size_t, int, int, ulong_t *, size_t))
--- 93,102 ----