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

@@ -166,17 +166,10 @@
         extern boolean_t tick_stick_emulation_active;
 #endif  /* sun4v */
 
         CPU_STATS_ADDQ(CPU, sys, trap, 1);
 
-#ifdef SF_ERRATA_23 /* call causes illegal-insn */
-        ASSERT((curthread->t_schedflag & TS_DONT_SWAP) ||
-            (type == T_UNIMP_INSTR));
-#else
-        ASSERT(curthread->t_schedflag & TS_DONT_SWAP);
-#endif /* SF_ERRATA_23 */
-
         if (USERMODE(rp->r_tstate) || (type & T_USER)) {
                 /*
                  * Set lwp_state before trying to acquire any
                  * adaptive lock
                  */

@@ -1370,12 +1363,10 @@
         uint32_t inst;
         utrap_handler_t *utrapp;
 
         CPU_STATS_ADDQ(CPU, sys, trap, 1);
 
-        ASSERT(curthread->t_schedflag & TS_DONT_SWAP);
-
         if (USERMODE(rp->r_tstate)) {
                 /*
                  * Set lwp_state before trying to acquire any
                  * adaptive lock
                  */