On Thu, 2005-10-20 at 13:27 -0400, Jeff Dike wrote:
> On Thu, Oct 20, 2005 at 08:11:05AM -0700, Badari Pulavarty wrote:
> > Initial plan was to use invalidate_inode_pages2_range(). But it didn't
> > really do what we wanted. So we ended up using truncate_inode_pages().
> > If it really works, then I plan to add truncate_inode_pages2_range()
> > to which works on a range of pages, instead of the whole file.
> > madvise(DONTNEED) followed by madvise(DISCARD) should be able to drop
> > all the pages in the given range.
> > 
> > Does this make sense ? Does this seem like right approach ?
> 
> Works for me.  I obviously have no idea about the wider vm implications of 
> this - that would be Hugh's territory :-)

Here is the latest version of madvise(DISCARD) I cooked up after 
talking to Darren.

Changes from previous:

1) madvise(DISCARD) - zaps the range and discards the pages. So, no
need to call madvise(DONTNEED) before.

2) I added truncate_inode_pages2_range() to just discard only the
range of pages - not the whole file.

Hugh, when you get a chance could you review this instead ?

Thanks,
Badari