SW_INVOL
flags = SW_INVOL | SW_PREEMPT;
KASSERT((flags & (SW_INVOL | SW_VOL)) != 0,
((flags & SW_PREEMPT) != 0 || ((flags & SW_INVOL) != 0 &&
mi_switch(SW_INVOL | SWT_NEEDRESCHED);
mi_switch(SW_INVOL | SWT_SUSPEND);
flags = SW_INVOL | SW_PREEMPT;
flags = SW_INVOL | SW_PREEMPT;