> > >I'm not fully sure why, but I'm more comfortable with this complexity 
> > >in
> > >the lock manager.
> > 
> > I'm not.  The more overhead the locking primitives we have are (and 
> > lockmgr is pretty heavy-weight), we can pretty much never hope to have 
> > a scalable MP implementation.
> > 
> > Put complexity in the things that require it, don't add complexity to 
> > places where it is seldom needed.
> 
> Is this one possible? Should add no overhead to the lock manager.

> void
> transferlockers(struct lock *from, struct lock *to)
> {
> 	if (from->lk_waitcount == 0)
> 		return;
> 
> 	if (from->lk_flags & LK_WAITDRAIN)
> 		transfer_sleepers((void *)&from->lk_flags,
> 		    (void *)&to->lk_flags);
> 	else
> 		transfer_sleepers((void *)from, (void *)to);
> }

i don't think it works because it won't switch "lkp" in acquire().

YAMAMOTO Takashi