From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751922AbZHRUut (ORCPT ); Tue, 18 Aug 2009 16:50:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751461AbZHRUut (ORCPT ); Tue, 18 Aug 2009 16:50:49 -0400 Received: from gir.skynet.ie ([193.1.99.77]:33144 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751432AbZHRUus (ORCPT ); Tue, 18 Aug 2009 16:50:48 -0400 Date: Tue, 18 Aug 2009 21:50:50 +0100 From: Mel Gorman To: Christoph Lameter Cc: Linux Memory Management List , Nick Piggin , Linux Kernel Mailing List Subject: Re: [PATCH 3/3] page-allocator: Move pcp static fields for high and batch off-pcp and onto the zone Message-ID: <20090818205050.GA756@csn.ul.ie> References: <1250594162-17322-1-git-send-email-mel@csn.ul.ie> <1250594162-17322-4-git-send-email-mel@csn.ul.ie> <20090818164216.GA13435@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 18, 2009 at 01:56:22PM -0400, Christoph Lameter wrote: > On Tue, 18 Aug 2009, Mel Gorman wrote: > > > On Tue, Aug 18, 2009 at 10:18:48AM -0400, Christoph Lameter wrote: > > > > > > This will increase the cache footprint for the hot code path. Could these > > > new variable be moved next to zone fields that are already in use there? > > > The pageset array is used f.e. > > > > > > > pageset is ____cacheline_aligned_in_smp so putting pcp->high/batch near > > it won't help in terms of cache footprint. This is why I located it near > > watermarks because it's known they'll be needed at roughly the same time > > pcp->high/batch would be normally accessed. > > watermarks are not accessed from the hot code path in free_hot_cold page. > They are used in a commonly-used path for allocation so there is some advantage. Put beside pageset, there is no advantage as that structure is already aligned to a cache-line. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab