> Looking at that list, I got the feeling that you'd want to
> push that PG-awareness down into the block-io layer as well,
> then, so as to be able to optimise for (perhaps) conflicting
> goals depending on what the app does; for the IO system to be
> able to read the apps mind it needs to have some knowledge of
> what the app is / needs / wants and I get the impression that
> this awareness needs to go deeper than the FS only.
That's a fair point, it would need be a kernel patch really, although not
necessarily a very big one, more a case of looking at FDs and if they're
flagged in some way then get the PGfs to do the job instead of/as well as
the normal code path.