From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932706AbXCUQIu (ORCPT ); Wed, 21 Mar 2007 12:08:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932710AbXCUQIu (ORCPT ); Wed, 21 Mar 2007 12:08:50 -0400 Received: from one.firstfloor.org ([213.235.205.2]:43984 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932706AbXCUQIu (ORCPT ); Wed, 21 Mar 2007 12:08:50 -0400 Date: Wed, 21 Mar 2007 17:08:46 +0100 From: Andi Kleen To: Eric Dumazet Cc: Andi Kleen , Andrew Morton , Christoph Lameter , linux kernel Subject: Re: [RFC, PATCH] SLAB : [NUMA] keep nodeid in struct page instead of struct slab Message-ID: <20070321160846.GA25583@one.firstfloor.org> References: <20070321102231.7288f231.dada1@cosmosbay.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070321102231.7288f231.dada1@cosmosbay.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 21, 2007 at 10:22:31AM +0100, Eric Dumazet wrote: > In order to avoid a cache miss in kmem_cache_free() on NUMA and reduce hot path length, we could exploit the following common facts. > > 1) MAX_NUMNODES <= 64 > > 2) alignment of 'struct kmem_cache *' can be >= 64 > > The following patch changes the page->lru.next to contain not only the 'struct kmem_cache *' pointer, but also the nodeid in the low order bits. > It might be cleaner to just put it into flags on 64bit. There is enough space there and we don't really care about 32bit NUMA machines. -Andi