Alexander Viro wrote:
>
> On Wed, 26 Jul 2000, Stephen C. Tweedie wrote:
>
> > For tail writes, I'd imagine we would just end up using the page cache
> > as a virtual cache as NFS uses it, and doing plain copy into the
> > buffer cache pages.
>
> Ouch. I _really_ don't like it - we end up with special behaviour on one
> page in the pagecache. And getting data migration from buffer cache to
> page cache, which is Not Nice(tm). Yuck... Besides, when do we decide that
> tail is going to be, erm, merged? What will happen with the page then?
Notwithstanding the fact that I intend to try to figure this out for myself over
the weekend by reading the code, could I please have a simple explanation of the
relationship between the page cache and buffer cache?
Specific questions: What shall we call the struct that describes a page - a page
header? This is a descriptor for a virtual page or a physical page? (I think:
physical page.) What exactly is the function of the list of buffer pages
hanging off a page descriptor? Do these hold the filesystem blocks that map the
page in virtual memory?
I'm sure all of this was discussed somewhere on the kernel list sometime in the
past, and I missed it.
--
Daniel
