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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F272DC433F5 for ; Mon, 14 Feb 2022 12:17:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352836AbiBNMRo (ORCPT ); Mon, 14 Feb 2022 07:17:44 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:49878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352782AbiBNMRj (ORCPT ); Mon, 14 Feb 2022 07:17:39 -0500 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8553488B4 for ; Mon, 14 Feb 2022 04:17:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644841051; x=1676377051; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=WNcZp4uku3WfwnM4/G/GcJDbdhFAcwmSC9YYrXd0/og=; b=S6RL+FrmITITg6PvfYnqXIomvaeF+ta+aor5LXUjW2et6cLHmMmDQbRq D111NrlbIwcF3OzMd8pbch1bvUxOsAqtA+f0CL/+1lMzwUyNlg423f7qR KdplclpTeusj8ogs1FodUpGRmu7t5mxy55NaZbLXP6wvL71hco+F3ROMM /lwJ872s6wU6OI0MyOWiObZmHGkoPlc4ZfzPAMFAhqSTOTdhwT0+CiUCN DuZ2ywhWYUtYmKm4zPXC1e9ANRxSY/CoUwfvqiDlm8TIcnrkEU9ZK/LcO R9DYnYg6yQq+LKV/OKxLGjGQBrEvv7Pg1eY4WMluAJ3yZSPMba4W3KFW2 w==; X-IronPort-AV: E=McAfee;i="6200,9189,10257"; a="247672899" X-IronPort-AV: E=Sophos;i="5.88,367,1635231600"; d="scan'208";a="247672899" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Feb 2022 04:17:31 -0800 X-IronPort-AV: E=Sophos;i="5.88,367,1635231600"; d="scan'208";a="528135824" Received: from yhuang6-desk2.sh.intel.com ([10.239.13.11]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Feb 2022 04:17:29 -0800 From: Huang Ying To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Huang Ying , Valentin Schneider , Ingo Molnar , Mel Gorman , Rik van Riel , Srikar Dronamraju Subject: [PATCH -V3 2/2] NUMA balancing: avoid to migrate task to CPU-less node Date: Mon, 14 Feb 2022 20:15:53 +0800 Message-Id: <20220214121553.582248-2-ying.huang@intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220214121553.582248-1-ying.huang@intel.com> References: <20220214121553.582248-1-ying.huang@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In a typical memory tiering system, there's no CPU in slow (PMEM) NUMA nodes. But if the number of the hint page faults on a PMEM node is the max for a task, The current NUMA balancing policy may try to place the task on the PMEM node instead of DRAM node. This is unreasonable, because there's no CPU in PMEM NUMA nodes. To fix this, CPU-less nodes are ignored when searching the migration target node for a task in this patch. To test the patch, we run a workload that accesses more memory in PMEM node than memory in DRAM node. Without the patch, the PMEM node will be chosen as preferred node in task_numa_placement(). While the DRAM node will be chosen instead with the patch. Known issue: I don't have systems to test complex NUMA topology type, for example, NUMA_BACKPLANE or NUMA_GLUELESS_MESH. v3: - Fix several missing places to use CPU-less nodes as migrating target. Signed-off-by: "Huang, Ying" Cc: Peter Zijlstra Cc: Valentin Schneider Cc: Ingo Molnar Cc: Mel Gorman Cc: Rik van Riel Cc: Srikar Dronamraju --- kernel/sched/fair.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 04968f3f9b6d..a3f0ea216ccb 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1988,7 +1988,7 @@ static int task_numa_migrate(struct task_struct *p) */ ng = deref_curr_numa_group(p); if (env.best_cpu == -1 || (ng && ng->active_nodes > 1)) { - for_each_online_node(nid) { + for_each_node_state(nid, N_CPU) { if (nid == env.src_nid || nid == p->numa_preferred_nid) continue; @@ -2086,13 +2086,13 @@ static void numa_group_count_active_nodes(struct numa_group *numa_group) unsigned long faults, max_faults = 0; int nid, active_nodes = 0; - for_each_online_node(nid) { + for_each_node_state(nid, N_CPU) { faults = group_faults_cpu(numa_group, nid); if (faults > max_faults) max_faults = faults; } - for_each_online_node(nid) { + for_each_node_state(nid, N_CPU) { faults = group_faults_cpu(numa_group, nid); if (faults * ACTIVE_NODE_FRACTION > max_faults) active_nodes++; @@ -2246,7 +2246,7 @@ static int preferred_group_nid(struct task_struct *p, int nid) dist = sched_max_numa_distance; - for_each_online_node(node) { + for_each_node_state(node, N_CPU) { score = group_weight(p, node, dist); if (score > max_score) { max_score = score; @@ -2265,7 +2265,7 @@ static int preferred_group_nid(struct task_struct *p, int nid) * inside the highest scoring group of nodes. The nodemask tricks * keep the complexity of the search down. */ - nodes = node_online_map; + nodes = node_states[N_CPU]; for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) { unsigned long max_faults = 0; nodemask_t max_group = NODE_MASK_NONE; @@ -2404,6 +2404,21 @@ static void task_numa_placement(struct task_struct *p) } } + /* Cannot migrate task to CPU-less node */ + if (!node_state(max_nid, N_CPU)) { + int near_nid = max_nid; + int distance, near_distance = INT_MAX; + + for_each_node_state(nid, N_CPU) { + distance = node_distance(max_nid, nid); + if (distance < near_distance) { + near_nid = nid; + near_distance = distance; + } + } + max_nid = near_nid; + } + if (ng) { numa_group_count_active_nodes(ng); spin_unlock_irq(group_lock); -- 2.30.2