static void
dump(Timers *tt)
{
	int i, j;
	Wheel *w;
	Timer *t;

	for(i = 0; i < NWHEEL; i++){
		w = &tt->wheels[i];
		iprint("wheel %d\n", i);
		for(j = w->idx; j < w->idx+NSLOT; j++){
			if((t = slot(tt, i, j)) == nil)
				continue;
			iprint("\tslot[%d]: ", j);
			for(; t != nil; t = t->tnext)
				iprint("@%lld ", t->twhen);
			iprint("\n");
		}
	}
}