Turn on preemption by default on the alpha arch. This also removes the

PREEMPTION kernel option.

Not objected to by:	-alpha

sys/alpha/alpha/interrupt.c

@@ -34,7 +34,6 @@
  */
 
 #include "opt_ddb.h"
-#include "opt_preemption.h"
 
 #include <sys/cdefs.h>			/* RCS ID & Copyright macro defns */
 
@@ -445,11 +444,7 @@ alpha_dispatch_intr(void *frame, unsigned long vector)
 		    "alpha_dispatch_intr: disabling vector 0x%x", i->vector);
 		ithd->it_disable(ithd->it_vector);
 	}
-#ifdef PREEMPTION
 	error = ithread_schedule(ithd, !cold);
-#else
-	error = ithread_schedule(ithd, 0);
-#endif
 	KASSERT(error == 0, ("got an impossible stray interrupt"));
 }
 

sys/conf/options.alpha

@@ -20,7 +20,6 @@ API_UP1000		opt_cpu.h
 PPC_PROBE_CHIPSET       opt_ppc.h
 PPC_DEBUG               opt_ppc.h
 
-PREEMPTION
 SHOW_BUSYBUFS
 PANIC_REBOOT_WAIT_TIME	opt_panic.h