From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 0BA6C8D0040 for ; Thu, 31 Mar 2011 00:57:54 -0400 (EDT) Message-ID: <4D940985.7020609@snapgear.com> Date: Thu, 31 Mar 2011 14:56:37 +1000 From: Greg Ungerer MIME-Version: 1.0 Subject: Re: [RFC/RFT 0/6] nommu: improve the vma list handling References: <1301320607-7259-1-git-send-email-namhyung@gmail.com> <20110328150102.11bcfca8.akpm@linux-foundation.org> In-Reply-To: <20110328150102.11bcfca8.akpm@linux-foundation.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Namhyung Kim , Paul Mundt , David Howells , linux-mm@kvack.org, linux-kernel@vger.kernel.org On 29/03/11 08:01, Andrew Morton wrote: > On Mon, 28 Mar 2011 22:56:41 +0900 > Namhyung Kim wrote: > >> When I was reading nommu code, I found that it handles the vma list/tree in >> an unusual way. IIUC, because there can be more than one identical/overrapped >> vmas in the list/tree, it sorts the tree more strictly and does a linear >> search on the tree. But it doesn't applied to the list (i.e. the list could >> be constructed in a different order than the tree so that we can't use the >> list when finding the first vma in that order). >> >> Since inserting/sorting a vma in the tree and link is done at the same time, >> we can easily construct both of them in the same order. And linear searching >> on the tree could be more costly than doing it on the list, it can be >> converted to use the list. >> >> Also, after the commit 297c5eee3724 ("mm: make the vma list be doubly linked") >> made the list be doubly linked, there were a couple of code need to be fixed >> to construct the list properly. >> >> Patch 1/6 is a preparation. It maintains the list sorted same as the tree and >> construct doubly-linked list properly. Patch 2/6 is a simple optimization for >> the vma deletion. Patch 3/6 and 4/6 convert tree traversal to list traversal >> and the rest are simple fixes and cleanups. >> >> Note that I don't have a system to test on, so these are *totally untested* >> patches. There could be some basic errors in the code. In that case, please >> kindly let me know. :) >> >> Anyway, I just compiled them on my x86_64 desktop using this command: >> >> make mm/nommu.o >> >> (Of course this required few of dirty-fixes to proceed) >> >> Also note that these are on top of v2.6.38. >> >> Any comments are welcome. > > That seems like a nice set of changes. There isn't much I can do with > them at this tims - hopefully some of the nommu people will be able to > find time to review and test the patches. That does seem like a nice set of changes. I have compiled and run tested on my ColdFire non-mmu targets, and it looks good. So for the whole series from me that is: Acked-by: Greg Ungerer > (Is there a way in which one can run a nommu kernel on a regular PC? Under > an emulator?) There is some around. Though none I have used I could recommend off hand. I have used Skyeye for emulating non-mmu ARM on a PC, but the mainline kernel lacks a serial driver for console on that (limiting its current usefullnedd quite a bit). I ran the freely available ColdFire one many years ago, bu I haven't tried it recently. Regards Greg ------------------------------------------------------------------------ Greg Ungerer -- Principal Engineer EMAIL: gerg@snapgear.com SnapGear Group, McAfee PHONE: +61 7 3435 2888 8 Gardner Close FAX: +61 7 3217 5323 Milton, QLD, 4064, Australia WEB: http://www.SnapGear.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org