Re: CVS commit: syssrc/sys/miscfs/nullfs

[Bill Studenmund <wrstuden%netbsd.org@localhost>]

On 11 Mar 2002, enami tsugutomo wrote:

> Bill Studenmund <wrstuden%netbsd.org@localhost> writes:
>
> > vnodes in general are expensive to build. I think it's good for us
> > to keep them around.
>
> I'm not sure nullfs is in the general case.  At least cost of building
> vnode may differ between file systems.

I agree it does differ. But I think if we want to be able to do anything
in a performant manner, we need the cache.

> > To fix it means changing the vnode interface (we need to add a way
> > for upper vnodes to register themselves, and for lower ones to send
> > info to upper ones).
>
> Or, implement cache without keeping reference to lower vnode (as
> commented in source).  Is keeping reference just for caching really
> good?

I really don't see how we would keep the cache otherwise. What would we
(reliably) cache on otherwise? If we don't keep the reference, the vnode
can get recycled under us, and then all hell can break loose.

Take care,

Bill