From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161187AbWASOAr (ORCPT ); Thu, 19 Jan 2006 09:00:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161203AbWASOAr (ORCPT ); Thu, 19 Jan 2006 09:00:47 -0500 Received: from mx1.suse.de ([195.135.220.2]:59778 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S1161187AbWASOAr (ORCPT ); Thu, 19 Jan 2006 09:00:47 -0500 Date: Thu, 19 Jan 2006 15:00:39 +0100 From: Nick Piggin To: Linus Torvalds Cc: Nick Piggin , Linux Memory Management , Linux Kernel Mailing List , Hugh Dickins , Andrew Morton , Andrea Arcangeli , David Miller Subject: Re: [patch 0/4] mm: de-skew page refcount Message-ID: <20060119140039.GA958@wotan.suse.de> References: <20060118024106.10241.69438.sendpatchset@linux.site> <20060118170558.GE28418@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 18, 2006 at 11:27:13AM -0800, Linus Torvalds wrote: > > > On Wed, 18 Jan 2006, Nick Piggin wrote: > > > > > So I disagree with this patch series. It has real downsides. There's a > > > reason we have the offset. > > > > Yes, there is a reason, I detailed it in the changelog and got rid of it. > > And I'm not applying it. I'd be crazy to replace good code by code that is > objectively _worse_. > And you're not? Damn. > The fact that you _document_ that it's worse doesn't make it any better. > > The places that you improve (in the other patches) seem to have nothing at > all to do with the counter skew issue, so I don't see the point. > You know, I believe you're right. I needed the de-skewing patch for something unrelated and it seemed that it opened the possibility for the following optimisations (ie. because we no longer touch a page after its refcount goes to zero). But actually it doesn't matter that we might touch page_count, only that we not clear PageLRU. So the enabler is simply moving the TestClearPageLRU after the get_page_testone. So I'll respin the patches without the de-skewing and the series will become much smaller and neater. > So let me repeat: WHY DID YOU MAKE THE CODE WORSE? > You've never bothered me about that until now... Thanks for the feedback! Nick