SW_PREEMPT
flags = SW_INVOL | SW_PREEMPT;
((flags & SW_PREEMPT) != 0 || ((flags & SW_INVOL) != 0 &&
(flags & SW_PREEMPT) != 0;
flags = SW_INVOL | SW_PREEMPT;
(flags & SW_PREEMPT) != 0;
flags = SW_INVOL | SW_PREEMPT;