From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754726AbYHUCNo (ORCPT ); Wed, 20 Aug 2008 22:13:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752664AbYHUCNe (ORCPT ); Wed, 20 Aug 2008 22:13:34 -0400 Received: from relay2.sgi.com ([192.48.171.30]:56475 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750801AbYHUCNd (ORCPT ); Wed, 20 Aug 2008 22:13:33 -0400 Date: Wed, 20 Aug 2008 21:13:32 -0500 From: Robin Holt To: Christoph Lameter Cc: KOSAKI Motohiro , LKML , linux-mm , Andrew Morton , tokunaga.keiich@jp.fujitsu.com Subject: Re: [RFC][PATCH 0/2] Quicklist is slighly problematic. Message-ID: <20080821021332.GA23397@sgi.com> References: <20080820195021.12E7.KOSAKI.MOTOHIRO@jp.fujitsu.com> <48AC25E7.4090005@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48AC25E7.4090005@linux-foundation.org> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 20, 2008 at 09:10:47AM -0500, Christoph Lameter wrote: > KOSAKI Motohiro wrote: > > Hi Cristoph, > > > > Thank you for explain your quicklist plan at OLS. > > > > So, I made summary to issue of quicklist. > > if you have a bit time, Could you please read this mail and patches? > > And, if possible, Could you please tell me your feeling? > > I believe what I said at the OLS was that quicklists are fundamentally crappy > and should be replaced by something that works (Guess that is what you meant > by "plan"?). Quicklists were generalized from the IA64 arch code. > > Good fixup but I would think that some more radical rework is needed. > > Maybe some of this needs to vanish into the TLB handling logic? > > Then I have thought for awhile that the main reason that quicklists exist are > the performance problems in the page allocator. If you can make the single > page alloc / free pass competitive in performance with quicklists then we > could get rid of all uses. It is more than the free/alloc cycle, the quicklist saves us from having to zero the page. In a sparsely filled page table, it saves time and cache footprint. In a heavily used page table, you end up with a near wash. One problem I see is somebody got rid of the node awareness. We used to not put pages onto a quicklist when they were being released from a different node than the cpu is on. Not sure where that went. It was done because of the trap page problem described here. Thanks, Robin