From nobody Sun Dec 14 12:16:33 2025 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 2E337C001DC for ; Thu, 27 Jul 2023 06:39:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232378AbjG0GjG (ORCPT ); Thu, 27 Jul 2023 02:39:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35904 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232193AbjG0GjF (ORCPT ); Thu, 27 Jul 2023 02:39:05 -0400 Received: from mgamail.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4007B211C for ; Wed, 26 Jul 2023 23:39:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1690439944; x=1721975944; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=gUXqBihJZoZ1Pmai0lJ204qnaiDMkb9JwZjj8InTaZc=; b=cm8VOyHLWxH3hb0BSCMV0gGOajMCl02SxzyxctQkizFHtR7MdAXflfwj c+S7owqC4aX8TFAZDwOWbfnL+LBHnLeVxiD7bKHoJdj23PR7rl8zblkgh krrTlCjUUuId+wW4OJGa+wjuNZcyiGebyvUVLv5KNBlFGEUPYmz9HDFN5 WKNV4nS2Wjab1lXWVTOCzPa7Uw34A1RkzNssxOM38PkLd24940DGkDABC ODn65DxWNBA2H29q38/HArs5+ipfnbMfdyZU6QNEWqLl/OxDNGU7kGhw1 9/fsWjbH/zQB7OzQ+7SZGPUpTqaooPymNyEC2LFP70sQdXM8FUuzZ6XFl Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10783"; a="347829721" X-IronPort-AV: E=Sophos;i="6.01,234,1684825200"; d="scan'208";a="347829721" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jul 2023 23:39:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10783"; a="973430138" X-IronPort-AV: E=Sophos;i="6.01,234,1684825200"; d="scan'208";a="973430138" Received: from chenyu-dev.sh.intel.com ([10.239.62.164]) by fmsmga006.fm.intel.com with ESMTP; 26 Jul 2023 23:39:00 -0700 From: Chen Yu To: Peter Zijlstra , Vincent Guittot Cc: Ingo Molnar , Juri Lelli , Tim Chen , Mel Gorman , Dietmar Eggemann , K Prateek Nayak , "Gautham R . Shenoy" , Chen Yu , Aaron Lu , linux-kernel@vger.kernel.org, Chen Yu Subject: [RFC PATCH 3/7] sched/fair: Save a snapshot of sched domain total_load and total_capacity Date: Thu, 27 Jul 2023 22:34:50 +0800 Message-Id: <0d71de8648889fe8b202be376e97d581ff3f12ed.1690273854.git.yu.c.chen@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Save the total_load, total_capacity of the current sched domain in each periodic load balance. This statistic can be used later by CPU_NEWLY_IDLE load balance if it quits the scan earlier. Introduce a sched feature ILB_SNAPSHOT to control this. Code can check if sd_share->total_capacity is non-zero to verify if the stat is valid. In theory, if the system has reached a stable status, the total_capacity and total_load should not change dramatically. Signed-off-by: Chen Yu --- include/linux/sched/topology.h | 2 ++ kernel/sched/fair.c | 25 +++++++++++++++++++++++++ kernel/sched/features.h | 2 ++ 3 files changed, 29 insertions(+) diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h index c07f2f00317a..d6a64a2c92aa 100644 --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -82,6 +82,8 @@ struct sched_domain_shared { atomic_t nr_busy_cpus; int has_idle_cores; int nr_idle_scan; + unsigned long total_load; + unsigned long total_capacity; }; =20 struct sched_domain { diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b3e25be58e2b..edcfee9965cd 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10132,6 +10132,27 @@ static void update_idle_cpu_scan(struct lb_env *en= v, WRITE_ONCE(sd_share->nr_idle_scan, (int)y); } =20 +static void ilb_save_stats(struct lb_env *env, + struct sched_domain_shared *sd_share, + struct sd_lb_stats *sds) +{ + if (!sched_feat(ILB_SNAPSHOT)) + return; + + if (!sd_share) + return; + + /* newidle balance is too frequent */ + if (env->idle =3D=3D CPU_NEWLY_IDLE) + return; + + if (sds->total_load !=3D sd_share->total_load) + WRITE_ONCE(sd_share->total_load, sds->total_load); + + if (sds->total_capacity !=3D sd_share->total_capacity) + WRITE_ONCE(sd_share->total_capacity, sds->total_capacity); +} + /** * update_sd_lb_stats - Update sched_domain's statistics for load balancin= g. * @env: The load balancing environment. @@ -10140,6 +10161,7 @@ static void update_idle_cpu_scan(struct lb_env *env, =20 static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_sta= ts *sds) { + struct sched_domain_shared *sd_share =3D env->sd->shared; struct sched_group *sg =3D env->sd->groups; struct sg_lb_stats *local =3D &sds->local_stat; struct sg_lb_stats tmp_sgs; @@ -10209,6 +10231,9 @@ static inline void update_sd_lb_stats(struct lb_env= *env, struct sd_lb_stats *sd } =20 update_idle_cpu_scan(env, sum_util); + + /* save a snapshot of stats during periodic load balance */ + ilb_save_stats(env, sd_share, sds); } =20 /** diff --git a/kernel/sched/features.h b/kernel/sched/features.h index ee7f23c76bd3..3cb71c8cddc0 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -101,3 +101,5 @@ SCHED_FEAT(LATENCY_WARN, false) =20 SCHED_FEAT(ALT_PERIOD, true) SCHED_FEAT(BASE_SLICE, true) + +SCHED_FEAT(ILB_SNAPSHOT, true) --=20 2.25.1