From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933113Ab2FVOiX (ORCPT ); Fri, 22 Jun 2012 10:38:23 -0400 Received: from casper.infradead.org ([85.118.1.10]:40029 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762132Ab2FVOiV convert rfc822-to-8bit (ORCPT ); Fri, 22 Jun 2012 10:38:21 -0400 Message-ID: <1340375872.18025.77.camel@twins> Subject: Re: [PATCH -mm v2 01/11] mm: track free size between VMAs in VMA rbtree From: Peter Zijlstra To: Rik van Riel Cc: Rik van Riel , linux-mm@kvack.org, akpm@linux-foundation.org, aarcange@redhat.com, minchan@gmail.com, kosaki.motohiro@gmail.com, andi@firstfloor.org, hannes@cmpxchg.org, mel@csn.ul.ie, linux-kernel@vger.kernel.org Date: Fri, 22 Jun 2012 16:37:52 +0200 In-Reply-To: <4FE48054.5090407@redhat.com> References: <1340315835-28571-1-git-send-email-riel@surriel.com> <1340315835-28571-2-git-send-email-riel@surriel.com> <1340359115.18025.57.camel@twins> <4FE47D0E.3000804@redhat.com> <1340374439.18025.75.camel@twins> <4FE48054.5090407@redhat.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2012-06-22 at 10:25 -0400, Rik van Riel wrote: > On 06/22/2012 10:13 AM, Peter Zijlstra wrote: > > On Fri, 2012-06-22 at 10:11 -0400, Rik van Riel wrote: > >> > >> I am still trying to wrap my brain around your alternative > >> search algorithm, not sure if/how it can be combined with > >> arbitrary address limits and alignment... > > > > for alignment we can do: len += align - 1; > > We could, but that might lead us to returning -ENOMEM > when we actually have memory available. > > When you consider architectures like HPPA, which use > a pretty large alignment, but align everything the same, > chances are pretty much every freed hole will have the > right alignment... Well, if you don't your gap heap is next to useless and you'll revert to simply walking all gaps until you find a suitable one. I really worry about this search function of yours, its complexity is very non obvious.