Re: [PATCH 1/2] [RFC] Range tree implementation

[John Stultz]

On 03/20/2012 03:00 AM, Dmitry Adamushko wrote:
> Hi John,
>
> On 16 March 2012 23:51, John Stultz<john.stultz@xxxxxxxxxx>  wrote:
> > After Andrew suggested something like his mumbletree idea
> > to better store a list of ranges, I worked on a few different
> > approaches, and this is what I've finally managed to get working.
> >
> > I suspect range-tree isn't a totally accurate name, but I
> > couldn't quite make out the difference between range trees
> > and interval trees, so I just picked one to call it. Do
> > let me know if you have a better name.
> >
> > The idea of storing ranges in a tree is nice, but has a number
> > of complications. When adding a range, its possible that a
> > large range will consume and merge a number of smaller ranges.
> Have you considered using 'prio_tree' (include/linux/prio_tree.h)? If
> we aim at addressing a wide range of possible use-cases (different
> patterns of adding/removing volatile ranges), then, at first glance,
> prio_tree looks like a better approach.
I'll take a closer look at that!

> e.g. for the "consume and merge a number of smaller ranges" scenario
> above, prio_tree gives O(log n) [ O(log n + m) ] behavior iso O(m log
> n) in your case.
Yea, one of the items I was looking at yesterday was to improve the 
range insert/remove usage, since I end up starting each lookup from the 
root node over and over.  I'm thinking of adding a iterate-next type 
call so that we don't re-start the lookup each iteration of the loop 
once we've found an item.

Thanks again for the great feedback!

-john

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