From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 4066D6B005A for ; Wed, 18 Mar 2009 11:09:06 -0400 (EDT) Date: Wed, 18 Mar 2009 15:07:24 +0000 From: Mel Gorman Subject: Re: [PATCH 00/35] Cleanup and optimise the page allocator V3 Message-ID: <20090318150724.GB4629@csn.ul.ie> References: <1237196790-7268-1-git-send-email-mel@csn.ul.ie> <20090316104054.GA23046@wotan.suse.de> <20090316111906.GA6382@csn.ul.ie> <20090316113358.GA30802@wotan.suse.de> <20090316120216.GB6382@csn.ul.ie> <20090316122505.GD30802@wotan.suse.de> <20090316133232.GA24293@csn.ul.ie> <20090316155342.GH30802@wotan.suse.de> <20090316165628.GP24293@csn.ul.ie> <20090316170551.GI30802@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20090316170551.GI30802@wotan.suse.de> Sender: owner-linux-mm@kvack.org To: Nick Piggin Cc: Linux Memory Management List , Pekka Enberg , Rik van Riel , KOSAKI Motohiro , Christoph Lameter , Johannes Weiner , Linux Kernel Mailing List , Lin Ming , Zhang Yanmin , Peter Zijlstra List-ID: On Mon, Mar 16, 2009 at 06:05:51PM +0100, Nick Piggin wrote: > On Mon, Mar 16, 2009 at 04:56:28PM +0000, Mel Gorman wrote: > > On Mon, Mar 16, 2009 at 04:53:42PM +0100, Nick Piggin wrote: > > > So yes definitely I think there should be a very real impact on > > > higher order coalescing no matter what you do. > > > > > > > Because this is not straight-forward at all, I'll put lazy buddy onto > > the back-burner and exhaust all other possibilities before revisiting it > > again. > > If it is such a big improvement, I expect *most* people will want > it and we probably should do it. I'll be reinvestigating it in isolation. It's possible that high-order and compound pages on the PCP lists is enough of a delayed buddy merging that the benefit from lazy buddy is marginal. > But just that it will not play > nicely with fragmentation and so you'd need to look into it and > devise some way those users can tune it to be nicer. > Which is why I'm going to postpone it for now. > > > unmovable zone fragmentation is more important point because it > > > eventually can destroy the movable zone. > > > > > > > Which is why rmqueue_fallback() also merges up all buddies before making > > any decisions but I accept your points. > > Right, that merge of buddies will only be able to look at what is > currently free. Wheras non-lazy buddy can pull out higher orders > before reallocating them. > -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org