On Mon, 2010-10-18 at 10:56 -0700, Linus Torvalds wrote:
On Mon, Oct 18, 2010 at 9:48 AM, Eric Paris <eparis(a)redhat.com>
> 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
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....