* Eric Paris <eparis@xxxxxxxxxx> wrote: > On Mon, 2010-10-18 at 10:56 -0700, Linus Torvalds wrote: > > On Mon, Oct 18, 2010 at 9:48 AM, Eric Paris <eparis@xxxxxxxxxx> 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.... I think it would be fair to argue that #2 is the thing that should be fixed first and foremost - before touching any data structure details. Because if you fix #2 then all the other items will become no-op to 99.9% of the people who are affected by this bug today. It's also probably a much simpler fix for -stable, so should be done first, etc. If you do the data structure changes first then #2 will likely not be backportable standalone and #1 will be risky to backport - creating nasty dependencies. Thanks, Ingo _______________________________________________ kernel mailing list kernel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/kernel
