Re: ima: use of radix tree cache indexing == massive waste of memory?

H. Peter Anvin
2010-10-18T18:08:27Z

On 10/18/2010 09:48 AM, Eric Paris wrote:
>
> 1) IMA uses radix trees which end up wasting 500 bytes per inode because
> the key is too sparse. I've got a patch which uses an rbtree instead
> I'm testing and will send along shortly. I found it funny working on
> the patch to see that Documentation/rbtree.txt says "This differs from
> radix trees (which are used to efficiently store sparse arrays and thus
> use long integer indexes to insert/access/delete nodes)" Which flys in
> the face of this report.
>

Radix trees can efficiently store data associated with sparse keys *as
long as the keys are clustered*. For random key distributions, they
perform horribly.

-hpa