From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751352Ab0CIRMh (ORCPT ); Tue, 9 Mar 2010 12:12:37 -0500 Received: from nlpi157.sbcis.sbc.com ([207.115.36.171]:58846 "EHLO nlpi157.prodigy.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751078Ab0CIRMf (ORCPT ); Tue, 9 Mar 2010 12:12:35 -0500 Date: Tue, 9 Mar 2010 11:11:55 -0600 (CST) From: Christoph Lameter X-X-Sender: cl@router.home To: Mel Gorman cc: Christian Ehrhardt , linux-mm@kvack.org, Nick Piggin , Chris Mason , Jens Axboe , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] page-allocator: Under memory pressure, wait on pressure to relieve instead of congestion In-Reply-To: <20100309170123.GG4883@csn.ul.ie> Message-ID: References: <1268048904-19397-1-git-send-email-mel@csn.ul.ie> <1268048904-19397-2-git-send-email-mel@csn.ul.ie> <4B966F93.9060207@linux.vnet.ibm.com> <20100309170123.GG4883@csn.ul.ie> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 9 Mar 2010, Mel Gorman wrote: > Until it's timeout at least. It's still better than the current > situation of sleeping on congestion. Congestion may clear if memory becomes available in other zones. > The ideal would be waiting on a per-node basis. I'm just not liking having > to look up the node structure when freeing a patch of pages and making a > cache line in there unnecessarily hot. The node structure (pgdat) contains the zone structures. If you know the type of zone then you can calculate the pgdat address. > > But then an overallocated node may stall processes. If that node is full > > of unreclaimable memory then the process may never wake up? > Processes wake after a timeout. Ok that limits it but still we may be waiting for no reason.