Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755547Ab3GaILi (ORCPT ); Wed, 31 Jul 2013 04:11:38 -0400 Received: from cantor2.suse.de ([195.135.220.15]:43839 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753016Ab3GaILe (ORCPT ); Wed, 31 Jul 2013 04:11:34 -0400 Date: Wed, 31 Jul 2013 09:11:30 +0100 From: Mel Gorman To: Peter Zijlstra Cc: Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML Subject: Re: [PATCH 04/18] mm: numa: Do not migrate or account for hinting faults on the zero page Message-ID: <20130731081130.GF2296@suse.de> References: <1373901620-2021-1-git-send-email-mgorman@suse.de> <1373901620-2021-5-git-send-email-mgorman@suse.de> <20130717110053.GD17211@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20130717110053.GD17211@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1827 Lines: 51 On Wed, Jul 17, 2013 at 01:00:53PM +0200, Peter Zijlstra wrote: > On Mon, Jul 15, 2013 at 04:20:06PM +0100, Mel Gorman wrote: > > The zero page is not replicated between nodes and is often shared > > between processes. The data is read-only and likely to be cached in > > local CPUs if heavily accessed meaning that the remote memory access > > cost is less of a concern. This patch stops accounting for numa hinting > > faults on the zero page in both terms of counting faults and scheduling > > tasks on nodes. > > > > Signed-off-by: Mel Gorman > > --- > > mm/huge_memory.c | 9 +++++++++ > > mm/memory.c | 7 ++++++- > > 2 files changed, 15 insertions(+), 1 deletion(-) > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > index e4a79fa..ec938ed 100644 > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -1302,6 +1302,15 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, > > > > page = pmd_page(pmd); > > get_page(page); > > + > > + /* > > + * Do not account for faults against the huge zero page. The read-only > > + * data is likely to be read-cached on the local CPUs and it is less > > + * useful to know about local versus remote hits on the zero page. > > + */ > > + if (is_huge_zero_pfn(page_to_pfn(page))) > > + goto clear_pmdnuma; > > + > > src_nid = numa_node_id(); > > count_vm_numa_event(NUMA_HINT_FAULTS); > > if (src_nid == page_to_nid(page)) > > And because of: > > 5918d10 thp: fix huge zero page logic for page with pfn == 0 > Yes. Thanks. -- Mel Gorman SUSE Labs -- 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/