hi,

> > > 	Example where atime is updated when it shouldn't be.
> > > 	This is similar to when mail is delivered to a mailbox.
> > 
> > i guess it's due to (superfluous?) cache invalidation due to IO_APPEND.
> 
> It's worse than I thought. We were having a problem where procmail log
> files would sometimes contain a string of nulls between the entries.
> When trying to debug this, I found that NetBSD 2.0 is reading the ENTIRE
> file and then writing the last bit of data.

i guess it's a chunk of blocks, not entire file.
(yes, they're same for relatively small files.)

> In fact, it is not just
> writing the data which is to be appended to the file, it is writing the
> entire final block (4k blocks).

it's because UBC maintains dirtiness per-page basis.
(ie. it isn't due to a simple bug.)

YAMAMOTO Takashi