it's only necessary to alarm on one mach, not all of them.

Notes:
not true: the system misbehaves if we only run alarms on cpu0.

Reference: /n/sources/patch/sorry/alarm-once
Date: Fri May 17 22:26:15 CES 2013
Signed-off-by: quanstro@quanstro.net
Reviewed-by: geoff

--- /sys/src/9/port/portclock.c	Fri May 17 22:25:50 2013
+++ /sys/src/9/port/portclock.c	Fri May 17 22:25:49 2013
@@ -159,7 +159,8 @@
 		exit(0);
 	}
 
-	checkalarms();
+	if(m->machno == 0)
+		checkalarms();
 
 	if(up && up->state == Running)
 		hzsched();	/* in proc.c */