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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


 260          * userland can issue rdtsc, and initialize the TSC_AUX value
 261          * (the cpuid) for the rdtscp instruction on appropriately
 262          * capable hardware.
 263          */
 264         if (is_x86_feature(x86_featureset, X86FSET_TSC))
 265                 setcr4(getcr4() & ~CR4_TSD);
 266 
 267         if (is_x86_feature(x86_featureset, X86FSET_TSCP))
 268                 (void) wrmsr(MSR_AMD_TSCAUX, 0);
 269 
 270         if (is_x86_feature(x86_featureset, X86FSET_DE))
 271                 setcr4(getcr4() | CR4_DE);
 272 #endif /* __xpv */
 273 
 274         /*
 275          * initialize t0
 276          */
 277         t0.t_stk = (caddr_t)rp - MINFRAME;
 278         t0.t_stkbase = t0stack;
 279         t0.t_pri = maxclsyspri - 3;
 280         t0.t_schedflag = TS_LOAD | TS_DONT_SWAP;
 281         t0.t_procp = &p0;
 282         t0.t_plockp = &p0lock.pl_lock;
 283         t0.t_lwp = &lwp0;
 284         t0.t_forw = &t0;
 285         t0.t_back = &t0;
 286         t0.t_next = &t0;
 287         t0.t_prev = &t0;
 288         t0.t_cpu = cpu[0];
 289         t0.t_disp_queue = &cpu0_disp;
 290         t0.t_bind_cpu = PBIND_NONE;
 291         t0.t_bind_pset = PS_NONE;
 292         t0.t_bindflag = (uchar_t)default_binding_mode;
 293         t0.t_cpupart = &cp_default;
 294         t0.t_clfuncs = &sys_classfuncs.thread;
 295         t0.t_copyops = NULL;
 296         THREAD_ONPROC(&t0, CPU);
 297 
 298         lwp0.lwp_thread = &t0;
 299         lwp0.lwp_regs = (void *)rp;
 300         lwp0.lwp_procp = &p0;




 260          * userland can issue rdtsc, and initialize the TSC_AUX value
 261          * (the cpuid) for the rdtscp instruction on appropriately
 262          * capable hardware.
 263          */
 264         if (is_x86_feature(x86_featureset, X86FSET_TSC))
 265                 setcr4(getcr4() & ~CR4_TSD);
 266 
 267         if (is_x86_feature(x86_featureset, X86FSET_TSCP))
 268                 (void) wrmsr(MSR_AMD_TSCAUX, 0);
 269 
 270         if (is_x86_feature(x86_featureset, X86FSET_DE))
 271                 setcr4(getcr4() | CR4_DE);
 272 #endif /* __xpv */
 273 
 274         /*
 275          * initialize t0
 276          */
 277         t0.t_stk = (caddr_t)rp - MINFRAME;
 278         t0.t_stkbase = t0stack;
 279         t0.t_pri = maxclsyspri - 3;
 280         t0.t_schedflag = 0;
 281         t0.t_procp = &p0;
 282         t0.t_plockp = &p0lock.pl_lock;
 283         t0.t_lwp = &lwp0;
 284         t0.t_forw = &t0;
 285         t0.t_back = &t0;
 286         t0.t_next = &t0;
 287         t0.t_prev = &t0;
 288         t0.t_cpu = cpu[0];
 289         t0.t_disp_queue = &cpu0_disp;
 290         t0.t_bind_cpu = PBIND_NONE;
 291         t0.t_bind_pset = PS_NONE;
 292         t0.t_bindflag = (uchar_t)default_binding_mode;
 293         t0.t_cpupart = &cp_default;
 294         t0.t_clfuncs = &sys_classfuncs.thread;
 295         t0.t_copyops = NULL;
 296         THREAD_ONPROC(&t0, CPU);
 297 
 298         lwp0.lwp_thread = &t0;
 299         lwp0.lwp_regs = (void *)rp;
 300         lwp0.lwp_procp = &p0;