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    SubjectRe: ima: use of radix tree cache indexing == massive waste of memory?
    On Mon, 2010-10-18 at 10:56 -0700, Linus Torvalds wrote:
    > On Mon, Oct 18, 2010 at 9:48 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.
    > Please. Look at the report more carefully.
    > The radix tree memory use is disgusting. Yes. But it is absolutely NOT
    > sufficient to try to just fix that part. Go back, look at the original
    > report email, and this line in particular:
    > 2235648 2069791 92% 0.12K 69864 32 279456K iint_cache
    > There's 2.2 million iint_cache allocations too, each 128 bytes in
    > size. That's still a quarter _gigabyte_ of crap that adds zero value
    > at all.

    That was #2 in my list of things to fix:
    2) IMA creates an entire integrity structure for every inode even when
    most or all of this structure will not be needed.

    I'm stating with #1 since that was 2G of wasted space (thus far my
    switch to rbtree seems to be surviving an xfstest) so I expect to send
    the patch this afternoon. #2 should attack the size of the iint_cache
    entries. #3 should attack the scalability. I'm certainly hoping I
    didn't miss part of the report....


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