From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261928AbTLUA7n (ORCPT ); Sat, 20 Dec 2003 19:59:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261929AbTLUA7n (ORCPT ); Sat, 20 Dec 2003 19:59:43 -0500 Received: from fw.osdl.org ([65.172.181.6]:29104 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261928AbTLUA7m (ORCPT ); Sat, 20 Dec 2003 19:59:42 -0500 Date: Sat, 20 Dec 2003 17:00:42 -0800 From: Andrew Morton To: Rik van Riel Cc: linux-kernel@vger.kernel.org, ak@suse.de, mbligh@us.ibm.com Subject: Re: [PATCH] make try_to_free_pages walk zonelist Message-Id: <20031220170042.3feb6aa7.akpm@osdl.org> In-Reply-To: References: X-Mailer: Sylpheed version 0.9.4 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Rik van Riel wrote: > > In 2.6.0 both __alloc_pages() and the corresponding > wakeup_kswapd()s walk all zones in the zone list, > possibly spanning multiple nodes in a low numa factor > system like AMD64. > > Also, if lower_zone_protection is set in /proc, then > it may be possible that kswapd never cleans out data > in zones further down the zonelist and try_to_free_pages > needs to do that. > > However, in 2.6.0 try_to_free_pages() only frees pages > in the pgdat the first zone in the zonelist belongs to. > > This is probably the wrong behaviour, since both the > page allocator and the kswapd wakeup free things from > all zones on the zonelist. The following patch makes > try_to_free_pages() consistent with the allocator, by > passing the zonelist as an argument and freeing pages > from all zones in the list. hm, OK, so this should be a no-op for non-NUMA setups. Prior to merging such a change it would be nice to have confirmed before-and-after testing on real NUMA hardware. Rather than saying "gee, this should help", but never knowing how much it really did help. Could you suggest a suitable worklaod for Andi and Martin to test sometime? Meanwhile, I'll mmify it for a bit of soak testing, thanks.