Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752065AbaBNAOv (ORCPT ); Thu, 13 Feb 2014 19:14:51 -0500 Received: from e9.ny.us.ibm.com ([32.97.182.139]:43664 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751089AbaBNAOu (ORCPT ); Thu, 13 Feb 2014 19:14:50 -0500 Date: Thu, 13 Feb 2014 16:14:38 -0800 From: Nishanth Aravamudan To: David Rientjes Cc: Raghavendra K T , Andrew Morton , Fengguang Wu , David Cohen , Al Viro , Damien Ramonda , Jan Kara , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH V5] mm readahead: Fix readahead fail for no local memory and limit readahead pages Message-ID: <20140214001438.GB1651@linux.vnet.ibm.com> References: <52F4B8A4.70405@linux.vnet.ibm.com> <52F88C16.70204@linux.vnet.ibm.com> <52F8C556.6090006@linux.vnet.ibm.com> <52FC6F2A.30905@linux.vnet.ibm.com> <52FC98A6.1000701@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux 3.11.0-15-generic (x86_64) User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14021400-7182-0000-0000-000009D56AC1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13.02.2014 [14:41:04 -0800], David Rientjes wrote: > On Thu, 13 Feb 2014, Raghavendra K T wrote: > > > Thanks David, unfortunately even after applying that patch, I do not see > > the improvement. > > > > Interestingly numa_mem_id() seem to still return the value of a > > memoryless node. > > May be per cpu _numa_mem_ values are not set properly. Need to dig out .... > > > > I believe ppc will be relying on __build_all_zonelists() to set > numa_mem_id() to be the proper node, and that relies on the ordering of > the zonelist built for the memoryless node. It would be very strange if > local_memory_node() is returning a memoryless node because it is the first > zone for node_zonelist(GFP_KERNEL) (why would a memoryless node be on the > zonelist at all?). > > I think the real problem is that build_all_zonelists() is only called at > init when the boot cpu is online so it's only setting numa_mem_id() > properly for the boot cpu. Does it return a node with memory if you > toggle /proc/sys/vm/numa_zonelist_order? Do > > echo node > /proc/sys/vm/numa_zonelist_order > echo zone > /proc/sys/vm/numa_zonelist_order > echo default > /proc/sys/vm/numa_zonelist_order > > and check if it returns the proper value at either point. This will force > build_all_zonelists() and numa_mem_id() to point to the proper node since > all cpus are now online. > > So the prerequisite for CONFIG_HAVE_MEMORYLESS_NODES is that there is an > arch-specific set_numa_mem() that makes this mapping correct like ia64 > does. If that's the case, then it's (1) completely undocumented and (2) > Nishanth's patch is incomplete because anything that adds > CONFIG_HAVE_MEMORYLESS_NODES needs to do the proper set_numa_mem() for it > to be any different than numa_node_id(). I'm working on this latter bit now. I tried to mirror ia64, but it looks like they have CONFIG_USER_PERCPU_NUMA_NODE_ID, which powerpc doesn't. It seems like CONFIG_USER_PERCPU_NUMA_NODE_ID and CONFIG_HAVE_MEMORYLESS_NODES should be tied together in Kconfig? I'll keep working, but would appreciate any further insight. -Nish -- 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/