Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755328Ab0AUXer (ORCPT ); Thu, 21 Jan 2010 18:34:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755312Ab0AUXeq (ORCPT ); Thu, 21 Jan 2010 18:34:46 -0500 Received: from smtp-out.google.com ([216.239.44.51]:36945 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755310Ab0AUXeq (ORCPT ); Thu, 21 Jan 2010 18:34:46 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=dQL/w36IOOukqJXulPFtoBersBgXOes6FoyO8BT0dcKzxmCckMCojwOf5yvRrokSt TMkgysDjQfRwFirAL6u4A== Date: Thu, 21 Jan 2010 15:34:39 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Mel Gorman cc: Andrea Arcangeli , Christoph Lameter , Adam Litke , Avi Kivity , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 5/7] Add /proc trigger for memory compaction In-Reply-To: <20100121140948.GJ5154@csn.ul.ie> Message-ID: References: <1262795169-9095-1-git-send-email-mel@csn.ul.ie> <1262795169-9095-6-git-send-email-mel@csn.ul.ie> <20100120094813.GC5154@csn.ul.ie> <20100121140948.GJ5154@csn.ul.ie> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1363 Lines: 27 On Thu, 21 Jan 2010, Mel Gorman wrote: > > It would be helpful to be able to determine what is "compactable" at the > > same time by adding both global and per-node "compact_order" tunables that > > would default to HUGETLB_PAGE_ORDER. > > Well, rather than having a separate tunable, writing a number to > /proc/sys/vm/compact could indicate the order if that trigger is now > working system-wide. Would that be suitable? > Do you think you'll eventually find a need to call try_to_compact_pages() with a higher order than the one passed to the page allocator to limit "compaction thrashing" from fragmented frees to a zone where we're constantly compacting order-1 pages, for instance? I agree that memory compaction should always be used before direct reclaim for higher order allocations, but it may be more efficient to define a compact_min_order, tunable from userspace, that would avoid the need for constant order-1 compactions from subsequent page allocations. If that's a possibility, we may find a need for "compact_order", now renamed "compact_min_order", outside of the explicit trigger. -- 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/