Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933322AbaGURsF (ORCPT ); Mon, 21 Jul 2014 13:48:05 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:48439 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932647AbaGURsD (ORCPT ); Mon, 21 Jul 2014 13:48:03 -0400 Date: Mon, 21 Jul 2014 10:47:54 -0700 From: Nishanth Aravamudan To: Jiang Liu Cc: Andrew Morton , Mel Gorman , David Rientjes , Mike Galbraith , Peter Zijlstra , "Rafael J . Wysocki" , Rik van Riel , Johannes Weiner , "Srivatsa S. Bhat" , Dave Hansen , Tony Luck , linux-mm@kvack.org, linux-hotplug@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC Patch V1 28/30] mm: Update _mem_id_[] for every possible CPU when memory configuration changes Message-ID: <20140721174754.GE4156@linux.vnet.ibm.com> References: <1405064267-11678-1-git-send-email-jiang.liu@linux.intel.com> <1405064267-11678-29-git-send-email-jiang.liu@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1405064267-11678-29-git-send-email-jiang.liu@linux.intel.com> X-Operating-System: Linux 3.13.0-32-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: 14072117-5806-0000-0000-0000000866A9 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11.07.2014 [15:37:45 +0800], Jiang Liu wrote: > Current kernel only updates _mem_id_[cpu] for onlined CPUs when memory > configuration changes. So kernel may allocate memory from remote node > for a CPU if the CPU is still in absent or offline state even if the > node associated with the CPU has already been onlined. This just sounds like the topology information is being updated at the wrong place/time? That is, the memory is online, the CPU is being brought online, but isn't associated with any node? > This patch tries to improve performance by updating _mem_id_[cpu] for > each possible CPU when memory configuration changes, thus kernel could > always allocate from local node once the node is onlined. Ok, what is the impact? Do you actually see better performance? > We check node_online(cpu_to_node(cpu)) because: > 1) local_memory_node(nid) needs to access NODE_DATA(nid) > 2) try_offline_node(nid) just zeroes out NODE_DATA(nid) instead of free it > > Signed-off-by: Jiang Liu > --- > mm/page_alloc.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 0ea758b898fd..de86e941ed57 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3844,13 +3844,13 @@ static int __build_all_zonelists(void *data) > /* > * We now know the "local memory node" for each node-- > * i.e., the node of the first zone in the generic zonelist. > - * Set up numa_mem percpu variable for on-line cpus. During > - * boot, only the boot cpu should be on-line; we'll init the > - * secondary cpus' numa_mem as they come on-line. During > - * node/memory hotplug, we'll fixup all on-line cpus. > + * Set up numa_mem percpu variable for all possible cpus > + * if associated node has been onlined. > */ > - if (cpu_online(cpu)) > + if (node_online(cpu_to_node(cpu))) > set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu))); > + else > + set_cpu_numa_mem(cpu, NUMA_NO_NODE); > #endif -- 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/