rw_delay
static struct lock_delay_config __read_frequently rw_delay;
SYSCTL_U16(_debug_rwlock, OID_AUTO, delay_base, CTLFLAG_RW, &rw_delay.base,
SYSCTL_U16(_debug_rwlock, OID_AUTO, delay_max, CTLFLAG_RW, &rw_delay.max,
lock_delay_default_init(&rw_delay);
rowner_loops = max(10000, rw_delay.max);
lock_delay_arg_init(&lda, &rw_delay);
lock_delay_arg_init(&lda, &rw_delay);