From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261825AbVBTMfh (ORCPT ); Sun, 20 Feb 2005 07:35:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261826AbVBTMfh (ORCPT ); Sun, 20 Feb 2005 07:35:37 -0500 Received: from smtp207.mail.sc5.yahoo.com ([216.136.129.97]:65379 "HELO smtp207.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S261825AbVBTMf1 (ORCPT ); Sun, 20 Feb 2005 07:35:27 -0500 Message-ID: <4218840D.6030203@yahoo.com.au> Date: Sun, 20 Feb 2005 23:35:25 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.5) Gecko/20050105 Debian/1.7.5-1 X-Accept-Language: en MIME-Version: 1.0 To: Andi Kleen CC: "David S. Miller" , benh@kernel.crashing.org, torvalds@osdl.org, akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] page table iterators References: <4214A1EC.4070102@yahoo.com.au> <4214A437.8050900@yahoo.com.au> <20050217194336.GA8314@wotan.suse.de> <1108680578.5665.14.camel@gaston> <20050217230342.GA3115@wotan.suse.de> <20050217153031.011f873f.davem@davemloft.net> <20050217235719.GB31591@wotan.suse.de> In-Reply-To: <20050217235719.GB31591@wotan.suse.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: > On Thu, Feb 17, 2005 at 03:30:31PM -0800, David S. Miller wrote: > >>On Fri, 18 Feb 2005 00:03:42 +0100 >>Andi Kleen wrote: >> >> >>>And to be honest we only have about 6 or 7 of these walkers >>>in the whole kernel. And 90% of them are in memory.c >>>While doing 4level I think I changed all of them around several >>>times and it wasn't that big an issue. So it's not that we >>>have a big pressing problem here... >> >>It's super error prone. A regression added by your edit of these > > > Actually it was in Nick's code (PUD layer ;-). But I won't argue > that my code didn't have bugs too... > > I won't look back to see where the error came from :) But yeah it is equally (if not more) likely to have come from me. And it probably did happen because all the code is slightly different and hard to understand. >>walkers for the 4level changes was only discovered and fixed >>yesterday by the ppc folks. >> >>I absolutely support any change which consolidates these things. > > > The problem is just that these walker macros when they > do all the lazy walking stuff will be quite complicated. > And I don't really want another uaccess.h-like macro mess. > > Yes currently they look simple, but that will change. > But even in that case, it will still be better to have the extra complexity once in the macro rather than throughout mm/ > Open coding is probably the smaller evil. > > And they're really not changed that often. > It is not so much a matter of changing, so much as having 10 slightly different implementations. I think it should be easier to go from the iterators patch to perhaps more complex iterators, or some open coding, etc etc. rather than try to put a big complex pt walker on top of these 10 different open coded implementations. But perhaps I'm missing something you're not - I'd need to see the lazy walking code I guess. Nick