From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933077Ab0JRSOW (ORCPT ); Mon, 18 Oct 2010 14:14:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52969 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933049Ab0JRSOV (ORCPT ); Mon, 18 Oct 2010 14:14:21 -0400 Subject: Re: ima: use of radix tree cache indexing == massive waste of memory? From: Eric Paris To: Linus Torvalds Cc: Kyle McMartin , James Morris , Christoph Hellwig , kernel@lists.fedoraproject.org, Mimi Zohar , warthog9@kernel.org, Dave Chinner , linux-kernel@vger.kernel.org, "H. Peter Anvin" , Serge Hallyn , Andrew Morton , mingo@elte.hu In-Reply-To: References: <20101016065206.GO4681@dastard> <20101016192027.GA6883@infradead.org> <20101017004945.GE1614@infradead.org> <20101017054008.GA16383@elte.hu> <20101017184652.GB28060@infradead.org> <20101018062530.GD8332@bombadil.infradead.org> <1287420534.2530.67.camel@localhost.localdomain> Content-Type: text/plain; charset="UTF-8" Date: Mon, 18 Oct 2010 14:13:16 -0400 Message-ID: <1287425596.2530.70.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.... -Eric