On Tue, Jun 28, 2005 at 10:35:55AM +0900, YAMAMOTO Takashi wrote:
> > description of these fields indicates we should note.
> 
> it's too expensive and unreasonable to detect every actual read of
> memory for atime update.

Sure.

> 
> if you consider mmap for read as a lazy implementation of read(2),
> it's appropriate to note it at mmap time.

It would be, but I don't see a problem with updating it when a page is faulted
in. 

> 
> > I realize we are being a bit fuzzy with things in that we do the updates 
> > in GETPAGES(). If I'm understanding how this works, if a page is resident 
> > and never gets pushed out, a process could keep using a page and we won't 
> > see subsequent updates to atime (or mtime). But I think what we're doing 
> > is better than just noting at mmap time.
> 
> it's what i called "randomly".
> 
> talking about mtime, i think it can be noted when the changes are
> flushed out to backing store.  ie. when we usually notice the dirtiness
> of the pages.

Yes, this is appropriate. Otherwise, tools like dump won't work properly.

> updating mtime in VOP_GETPAGES is somewhat improper, IMO.

It could be updated in VOP_PUTPAGES(), isn't it ?

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--