Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754656AbZIVACj (ORCPT ); Mon, 21 Sep 2009 20:02:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754542AbZIVACi (ORCPT ); Mon, 21 Sep 2009 20:02:38 -0400 Received: from hera.kernel.org ([140.211.167.34]:56263 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754397AbZIVACi (ORCPT ); Mon, 21 Sep 2009 20:02:38 -0400 Message-ID: <4AB813F3.8060102@kernel.org> Date: Tue, 22 Sep 2009 09:01:55 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.22 (X11/20090605) MIME-Version: 1.0 To: Mel Gorman CC: Nick Piggin , Pekka Enberg , Christoph Lameter , heiko.carstens@de.ibm.com, sachinp@in.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Benjamin Herrenschmidt Subject: Re: [PATCH 1/3] powerpc: Allocate per-cpu areas for node IDs for SLQB to use as per-node areas References: <1253549426-917-1-git-send-email-mel@csn.ul.ie> <1253549426-917-2-git-send-email-mel@csn.ul.ie> In-Reply-To: <1253549426-917-2-git-send-email-mel@csn.ul.ie> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Tue, 22 Sep 2009 00:01:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1694 Lines: 49 Hello, Mel Gorman wrote: > diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c > index 1f68160..a5f52d4 100644 > --- a/arch/powerpc/kernel/setup_64.c > +++ b/arch/powerpc/kernel/setup_64.c > @@ -588,6 +588,26 @@ void __init setup_per_cpu_areas(void) > paca[i].data_offset = ptr - __per_cpu_start; > memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start); > } > +#ifdef CONFIG_SLQB > + /* > + * SLQB abuses DEFINE_PER_CPU to setup a per-node area. This trick > + * assumes that ever node ID will have a CPU of that ID to match. > + * On systems with memoryless nodes, this may not hold true. Hence, > + * we take a second pass initialising a "per-cpu" area for node-ids > + * that SLQB can use > + */ > + for_each_node_state(i, N_NORMAL_MEMORY) { > + > + /* Skip node IDs that a valid CPU id exists for */ > + if (paca[i].data_offset) > + continue; > + > + ptr = alloc_bootmem_pages_node(NODE_DATA(cpu_to_node(i)), size); > + > + paca[i].data_offset = ptr - __per_cpu_start; > + memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start); > + } > +#endif /* CONFIG_SLQB */ > } > #endif Eh... I don't know. This seems too hacky to me. Why not just allocate pointer array of MAX_NUMNODES and allocate per-node memory there? This will be slightly more expensive but I doubt it will be noticeable. The only extra overhead is the cachline footprint for the extra array. Thanks. -- tejun -- 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/