From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5FAF1C433E9 for ; Fri, 5 Mar 2021 00:00:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2E2C264FFF for ; Fri, 5 Mar 2021 00:00:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231217AbhCEAAr (ORCPT ); Thu, 4 Mar 2021 19:00:47 -0500 Received: from mga09.intel.com ([134.134.136.24]:34007 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230112AbhCEAAo (ORCPT ); Thu, 4 Mar 2021 19:00:44 -0500 IronPort-SDR: NxNctiw5w5v76hIGt/2/oql6LsADURZ8CFNIXq1H4ZOrcPv5y6LsT0Ibkg2Nl7cFySu0IcOTov JelV2SZQc+lA== X-IronPort-AV: E=McAfee;i="6000,8403,9913"; a="187639168" X-IronPort-AV: E=Sophos;i="5.81,223,1610438400"; d="scan'208";a="187639168" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2021 16:00:43 -0800 IronPort-SDR: 59t9sYMm+sfUtqu57XK2tUdmjZALZ5z0CGslJWlBGy9fiQJWEwzPTQ5pCOqtEdEM+KzkZm6mM4 97qFnM9DYYlA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,223,1610438400"; d="scan'208";a="407034731" Received: from viggo.jf.intel.com (HELO localhost.localdomain) ([10.54.77.144]) by orsmga007.jf.intel.com with ESMTP; 04 Mar 2021 16:00:43 -0800 Subject: [PATCH 01/10] mm/numa: node demotion data structure and lookup To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Dave Hansen , yang.shi@linux.alibaba.com, rientjes@google.com, ying.huang@intel.com, dan.j.williams@intel.com, david@redhat.com, osalvador@suse.de From: Dave Hansen Date: Thu, 04 Mar 2021 15:59:51 -0800 References: <20210304235949.7922C1C3@viggo.jf.intel.com> In-Reply-To: <20210304235949.7922C1C3@viggo.jf.intel.com> Message-Id: <20210304235951.271553C2@viggo.jf.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen Prepare for the kernel to auto-migrate pages to other memory nodes with a user defined node migration table. This allows creating single migration target for each NUMA node to enable the kernel to do NUMA page migrations instead of simply reclaiming colder pages. A node with no target is a "terminal node", so reclaim acts normally there. The migration target does not fundamentally _need_ to be a single node, but this implementation starts there to limit complexity. If you consider the migration path as a graph, cycles (loops) in the graph are disallowed. This avoids wasting resources by constantly migrating (A->B, B->A, A->B ...). The expectation is that cycles will never be allowed. Signed-off-by: Dave Hansen Cc: Yang Shi Cc: David Rientjes Cc: Huang Ying Cc: Dan Williams Cc: David Hildenbrand Cc: osalvador -- changes since 20200122: * Make node_demotion[] __read_mostly changes in July 2020: - Remove loop from next_demotion_node() and get_online_mems(). This means that the node returned by next_demotion_node() might now be offline, but the worst case is that the allocation fails. That's fine since it is transient. --- b/mm/migrate.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff -puN mm/migrate.c~0006-node-Define-and-export-memory-migration-path mm/migrate.c --- a/mm/migrate.c~0006-node-Define-and-export-memory-migration-path 2021-03-04 15:35:51.353806441 -0800 +++ b/mm/migrate.c 2021-03-04 15:35:51.359806441 -0800 @@ -1157,6 +1157,23 @@ out: return rc; } +static int node_demotion[MAX_NUMNODES] __read_mostly = + {[0 ... MAX_NUMNODES - 1] = NUMA_NO_NODE}; + +/** + * next_demotion_node() - Get the next node in the demotion path + * @node: The starting node to lookup the next node + * + * @returns: node id for next memory node in the demotion path hierarchy + * from @node; NUMA_NO_NODE if @node is terminal. This does not keep + * @node online or guarantee that it *continues* to be the next demotion + * target. + */ +int next_demotion_node(int node) +{ + return node_demotion[node]; +} + /* * Obtain the lock on page, remove all ptes and migrate the page * to the newly allocated page in newpage. _