From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 82A9D600744 for ; Mon, 30 Nov 2009 15:28:45 -0500 (EST) Subject: Re: [PATCH/RFC 1/6] numa: Use Generic Per-cpu Variables for numa_node_id() From: Lee Schermerhorn In-Reply-To: References: <20091113211714.15074.29078.sendpatchset@localhost.localdomain> <20091113211720.15074.99808.sendpatchset@localhost.localdomain> Content-Type: text/plain Date: Mon, 30 Nov 2009 15:28:40 -0500 Message-Id: <1259612920.4663.156.camel@useless.americas.hpqcorp.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: linux-arch@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, Mel Gorman , Christoph Lameter , Nick Piggin , David Rientjes , eric.whitney@hp.com, Tejun Heo List-ID: On Fri, 2009-11-20 at 10:46 -0500, Christoph Lameter wrote: > On Fri, 13 Nov 2009, Lee Schermerhorn wrote: > > > Signed-off-by: Lee Schermerhorn > > [Christoph's signoff here?] > > Basically yes. The moving of the this_cpu ops to asm-generic is something > that is bothering me. Tejun? So here's what happened: linux/topology.h now depends on */percpu.h to implement numa_node_id() and numa_mem_id(). Not so much an issue for x86 because its asm/topology.h already depended on its asm/percpu.h. But ia64, for instance--maybe any arch that doesn't already implement numa_node_id() as a percpu variable--didn't define this_cpu_read() for linux/topology.h. So, I included . linux/percpu.h, for reasons of its own, includes linux/swap.h which includes linux/gfp.h which includes linux/topology.h for the definition of numa_node_id(). topology.h hasn't gotten around to defining numa_node_id() yet--it's still including percpu.h. ... Looking at other asm/foo.h and asm-generic/foo.h relationships, I see that some define the generic version of the api in the asm-generic header if the arch asm header hasn't already defined it. asm/topology.h is an instance of this. It includes asm-generic/topology.h after defining arch specific versions of some of the api. Following this model, I moved the generic definitions of the percpu api back to the asm-generic version where it would be available without the inclusion of swap.h, et al. I tried including in linux/topology.h but the was advised to use the generic header. So I followed the model of the x86 asm/topology.h and included asm/percpu.h in the ia64 asm/topology.h, making the definitions visible to linux/topology.h. This reminds me that I should add to the patch description a 3rd item required for an arch to use the generic percpu numa_node_id() implementation: make the percpu variable access interface visible via asm/topology.h. Does that sound reasonable? Lee -- 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