From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754511AbYHUCQj (ORCPT ); Wed, 20 Aug 2008 22:16:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752591AbYHUCQb (ORCPT ); Wed, 20 Aug 2008 22:16:31 -0400 Received: from relay1.sgi.com ([192.48.171.29]:36186 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751304AbYHUCQb (ORCPT ); Wed, 20 Aug 2008 22:16:31 -0400 Date: Wed, 20 Aug 2008 21:16:30 -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: <20080821021630.GB23397@sgi.com> References: <20080820195021.12E7.KOSAKI.MOTOHIRO@jp.fujitsu.com> <48AC25E7.4090005@linux-foundation.org> <20080821021332.GA23397@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080821021332.GA23397@sgi.com> 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 09:13:32PM -0500, Robin Holt wrote: > 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. Poorly worded. Here is the code I am referring to: #ifdef CONFIG_NUMA unsigned long nid = page_to_nid(virt_to_page(pgtable_entry)); if (unlikely(nid != numa_node_id())) { free_page((unsigned long)pgtable_entry); return; } #endif Thanks, Robin