Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968389AbWLEQAx (ORCPT ); Tue, 5 Dec 2006 11:00:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S968391AbWLEQAx (ORCPT ); Tue, 5 Dec 2006 11:00:53 -0500 Received: from omx2-ext.sgi.com ([192.48.171.19]:47179 "EHLO omx2.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S968389AbWLEQAw (ORCPT ); Tue, 5 Dec 2006 11:00:52 -0500 Date: Tue, 5 Dec 2006 08:00:39 -0800 (PST) From: Christoph Lameter To: Andrew Morton cc: Mel Gorman , Linux Memory Management List , Linux Kernel Mailing List Subject: Re: [PATCH] Add __GFP_MOVABLE for callers to flag allocations that may be migrated In-Reply-To: <20061204142259.3cdda664.akpm@osdl.org> Message-ID: References: <20061130170746.GA11363@skynet.ie> <20061130173129.4ebccaa2.akpm@osdl.org> <20061201110103.08d0cf3d.akpm@osdl.org> <20061204140747.GA21662@skynet.ie> <20061204113051.4e90b249.akpm@osdl.org> <20061204120611.4306024e.akpm@osdl.org> <20061204131959.bdeeee41.akpm@osdl.org> <20061204142259.3cdda664.akpm@osdl.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1685 Lines: 38 On Mon, 4 Dec 2006, Andrew Morton wrote: > > > What happens when we need to run reclaim against just a section of a zone? > > > Lumpy-reclaim could be used here; perhaps that's Mel's approach too? > > > > Why would we run reclaim against a section of a zone? > > Strange question. Because all the pages are in use for something else. We always run reclaim against the whole zone not against parts. Why would we start running reclaim against a portion of a zone? > > Mel aready has that for anti-frag. The sections are per MAX_ORDER area > > and the only states are movable unmovable and reclaimable. There is > > nothing more to it. No other state information should be added. Why would > > we need sub zones? For what purpose? > > You're proposing that for memory hot-unplug, we take a single zone and by > some means subdivide that into sections which correspond to physically > hot-unpluggable memory. That certainly does not map onto MAX_ORDER > sections. Mel's patches are already managing "sections" (if you want to call it that) of a zone in units of MAX_ORDER. If we memorize where the lowest unmovable MAX_ORDER block is then we have the necessary separation and can do memory unplug on the remainder of the zone. > > What feature are you talking about? > > Memory hot-unplug, of course. There are multiple issues that we discuss here. Please be clear. Categorical demands for perfection certainly wont help us. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/