Re: [RFC] [PATCH v5 0/3] fadvise: support POSIX_FADV_NOREUSE

[Andrea Righi <andrea@betterlinux.com>]

On Sun, Feb 12, 2012 at 03:16:07PM +0800, Hillf Danton wrote:
> Hello Andrea
> 
> On Sun, Feb 12, 2012 at 8:21 AM, Andrea Righi <andrea@betterlinux.com> wrote:
> [...]
> >  - Some of the routines to implement the generic interval tree has been taken
> >   from the x86 PAT code, that uses interval trees to keep track of PAT ranges
> >   (in the future it would be interesting to convert also the x86 PAT code to
> >   use the generic interval tree implementation).
> >
> Perhaps the tree implemented in this work could also be used in tracking
> regions in mm/hugetlb.c.
> 
> Thanks
> Hillf

Thanks, Hillf.

Yes, I quickly looked at the hugtlb code, it seems another potential
user of the interval tree. Now all the hugetlb regions are stored in a
list, the interval tree is a more efficient structure for lookups -
O(log(n)), so there are probably advantages in presence of many
different disjoint intervals.

mmh... at the moment there's not a way to map region_count() with the
current kinterval API, but we can easily extend it to provide also this
feature (count the overlap size of two intervals).

-Andrea