Received: by 2002:a05:6358:bb9e:b0:b9:5105:a5b4 with SMTP id df30csp5359339rwb; Wed, 7 Sep 2022 01:18:50 -0700 (PDT) X-Google-Smtp-Source: AA6agR6gjxjjmziYpvy3hPuctGkL36pUYFl1x+vU8n8Rrr5weCRFkVmYeF5/KsbtvuKucIZD/Tzo X-Received: by 2002:a17:902:be01:b0:176:8bc3:b379 with SMTP id r1-20020a170902be0100b001768bc3b379mr2807118pls.109.1662538730138; Wed, 07 Sep 2022 01:18:50 -0700 (PDT) Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id i27-20020a63221b000000b0043041b4e7efsi16529211pgi.740.2022.09.07.01.18.38; Wed, 07 Sep 2022 01:18:50 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=G3M0YgJR; arc=fail (signature failed); spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229830AbiIGH2a (ORCPT + 99 others); Wed, 7 Sep 2022 03:28:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229472AbiIGH21 (ORCPT ); Wed, 7 Sep 2022 03:28:27 -0400 Received: from mga06.intel.com (mga06b.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DBF89A2877 for ; Wed, 7 Sep 2022 00:28:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1662535706; x=1694071706; h=date:from:to:cc:subject:message-id:references: in-reply-to:mime-version; bh=+PbJd98wl92mCTMJceiRr9dRZAeuDpJM0tRRqvPaoDU=; b=G3M0YgJRaiVy/iq7l1REwDe7OgkR9LKx7ezwO+lUVjDHMMOCJljjehCV f+fTvfzoxpCeImW9btthhWU4jtwQNjpPw6IMsluGu3QpvjWkI0Dndotaz G5HjjpCef4JQoodPsgQVwNXJLRUr07fKltIYMnSfUK1fToZ7qB4fvsO7X FK1dSm6Wm0xS5F+vAtpyIsbY1/3K2HCO3LQEXEhBGoL0zHJGergx1wTN/ u2UjJKZ/ZecJJBaT82ro+w8eWty19EHFRkAsZMf+A+7Rskv6WM1CLANUD 8LmT+1SCiJ/kc6jaribKCyXf94lJ/icGOpEzkjbZSwtlT/6OzZMY0jvlg g==; X-IronPort-AV: E=McAfee;i="6500,9779,10462"; a="358519147" X-IronPort-AV: E=Sophos;i="5.93,296,1654585200"; d="scan'208";a="358519147" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Sep 2022 00:28:13 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,296,1654585200"; d="scan'208";a="610229473" Received: from fmsmsx601.amr.corp.intel.com ([10.18.126.81]) by orsmga007.jf.intel.com with ESMTP; 07 Sep 2022 00:28:10 -0700 Received: from fmsmsx608.amr.corp.intel.com (10.18.126.88) by fmsmsx601.amr.corp.intel.com (10.18.126.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Wed, 7 Sep 2022 00:28:03 -0700 Received: from fmsmsx608.amr.corp.intel.com (10.18.126.88) by fmsmsx608.amr.corp.intel.com (10.18.126.88) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Wed, 7 Sep 2022 00:28:03 -0700 Received: from fmsedg601.ED.cps.intel.com (10.1.192.135) by fmsmsx608.amr.corp.intel.com (10.18.126.88) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31 via Frontend Transport; Wed, 7 Sep 2022 00:28:03 -0700 Received: from NAM12-MW2-obe.outbound.protection.outlook.com (104.47.66.42) by edgegateway.intel.com (192.55.55.70) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2375.31; Wed, 7 Sep 2022 00:28:02 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ocurCcVwzCYNDnM2EqJho5I6Up9oqVAsMkouqtKppa+gt/zR96AU9eh0xT+YAZ0jY7gqFoAWc68fAjl1i2R0H3byYEwGXOpk9ljO3e9NvYISFgTmV0T8JPlUDLp9R6rbugVj340D8JbWFO7EFJyJNHfm1k4T4IOffhe+Dotsr9Qe8ruyty5n7M9JgWZjzxzXIWpmzyQGLcNLbEBNykB9dYGETWl7DMnGwq+OqSZs10+KO5X/kvcOs19v+ejPH0gjvTuPpGVd/qmoEUlrcdbTOlUeEaT9jtfS1M3ZDn6SBhRsdhU/90jgoq47vXteCLV1Vz3dlhhdKO6SeV7FYZHL9Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=uhbi5doAmqcOX5A1JdFqzGPxkKHR8+KicbbuU0JPxYk=; b=M4RbXkg22NrykgInI6IBNO+cbW5g0mLkDRcyUrPAMBpHmBFL//hlU70yEFT2V8QjFuBT7vKaGfDF7/MNZETGFkerRjVU3LSDBew7HIzg1kpQFadB90cIS40blaEbMAe7vQHPPQFVgYvNMddkRkQfTz/vxvSoeS0ql3AmdbWwc77l/PHTsjpO7qv6sLwGKu715QVggkyjKUz0g+moII7pPCxBGaMfbG5hhcuPdd8PRn62ETW4pNrswmQZVXvq6Y+Xjbv3phltUiE+mR3yMoJFxi4Soge/OtWeqG5WqE5m/RHp0ri6PLM1/FulUaLq+dvCyQTpjEJni22180qZI87jiQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com; Received: from MN0PR11MB6206.namprd11.prod.outlook.com (2603:10b6:208:3c6::8) by BYAPR11MB3415.namprd11.prod.outlook.com (2603:10b6:a03:81::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5612.14; Wed, 7 Sep 2022 07:28:00 +0000 Received: from MN0PR11MB6206.namprd11.prod.outlook.com ([fe80::7c1d:1bee:fe96:695c]) by MN0PR11MB6206.namprd11.prod.outlook.com ([fe80::7c1d:1bee:fe96:695c%6]) with mapi id 15.20.5588.017; Wed, 7 Sep 2022 07:28:00 +0000 Date: Wed, 7 Sep 2022 15:27:41 +0800 From: Chen Yu To: Mel Gorman CC: Abel Wu , Peter Zijlstra , Mel Gorman , Vincent Guittot , Josh Don , Subject: Re: [PATCH 1/5] sched/fair: ignore SIS_UTIL when has idle core Message-ID: References: <20220712082036.5130-1-wuyun.abel@bytedance.com> <20220712082036.5130-2-wuyun.abel@bytedance.com> <20220829130831.odhemmcmuecqxkbz@techsingularity.net> <51009414-5ffb-b6ec-a501-7b2514a0f3cc@bytedance.com> <20220829145621.7cxrywgxow5ov7ki@techsingularity.net> <0ffb0903-431f-88fe-3a56-150b283f5304@bytedance.com> <20220902102528.keooutttg3hq3sy5@techsingularity.net> <1fc40679-b7c3-24f2-aa27-f1edab71228e@bytedance.com> <20220906095717.maao4qtel4fhbmfq@techsingularity.net> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20220906095717.maao4qtel4fhbmfq@techsingularity.net> X-ClientProxiedBy: SGAP274CA0007.SGPP274.PROD.OUTLOOK.COM (2603:1096:4:b6::19) To MN0PR11MB6206.namprd11.prod.outlook.com (2603:10b6:208:3c6::8) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9f4ed383-a8c7-4a64-4b0b-08da90a27e13 X-MS-TrafficTypeDiagnostic: BYAPR11MB3415:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MN0PR11MB6206.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(7916004)(136003)(366004)(396003)(376002)(39860400002)(346002)(5660300002)(8936002)(2906002)(83380400001)(33716001)(66476007)(66946007)(38100700002)(8676002)(4326008)(66556008)(82960400001)(53546011)(6506007)(6916009)(54906003)(86362001)(478600001)(186003)(6512007)(316002)(9686003)(966005)(6486002)(41300700001)(6666004)(26005)(67856001);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?4gWnr/A8kIPPaJGFbw8sllYtJHgwNzjwuw/lykRs6ydymDw7ijyJZQ9vpBsL?= =?us-ascii?Q?GJTbipWJuw7oGvY2AhAn6qJPdsAGssSlZBbRl3iyvI7REz7XsBGyTNKhf1i/?= =?us-ascii?Q?X32z4ubftYc8bbUgc/Cil/L6AbOpvbusMfQt2lW7TmJ0WOwaLIsxBhIC++Zw?= =?us-ascii?Q?xNavGWiZicGqX2k4m8UJl18QyHMwPmYl2RohIIOUGkOi0IoNgRCMq6DobJB8?= =?us-ascii?Q?uMGrzJ5MhDnDHDs9Oe0OaXvuGCIzBV4GagufYKoJGEaJAFIWwH9INhFuJIn1?= =?us-ascii?Q?+4YPkX3MBbmnx6eUBsPBTMSY2SJaHN2FVQRqj0NGPxiuiv/nAyAG/hepSLZj?= =?us-ascii?Q?hL7N3DkxY+2nclThier3VrNHTQ338WvFz7ruhbSmA0M9J7Adk27Q3kP/T7S+?= =?us-ascii?Q?duonU4e2rcoHheMzst44Nkla7W3p6mOEJRGOG7RNPta/cKUkY/G3vWq/CLRU?= =?us-ascii?Q?VKpgNa7FLsercn8Xl4lol2QMDnkDBO/7t/HmzbiFTDLmnH37e3PUWPZE2rdC?= =?us-ascii?Q?BpGFTtFcuo0WoGhLHpsaZ6wyEpKBLz1CqNTsv7yIqDewfU06325ydw3V7WXT?= =?us-ascii?Q?k2tpfcEwpWjkZPCYM1wGgKmeqYPclt54m1U6hlonz4CwCOUaJOZ9KhHAzGm9?= =?us-ascii?Q?JjIEHlNSlnYJAIQ/KvBWmw13+SdLKr272vmeMA+wDR+IElC+ALnhKjFx6u3Z?= =?us-ascii?Q?QnZhu8D5EAoOgPkXEg3hJ9M6IiJYkMkUWMe77UgRnfuRf1XD3617i9RUmVNx?= =?us-ascii?Q?vmBPF9XZoT4V9hY7l6KSBDmGJmWdwUC0UdANLCBIC0/Dh7f/l6rv+DbRdwWh?= =?us-ascii?Q?byRKFSSIsfApJSNYe2gW+Vi3xFIL+w+qxiGBDn+hkGfxBq9Nyhm1AwoEXuSl?= =?us-ascii?Q?tNS6Iv6NhAkd9eWp3u831KJ7QtwZGNjbpSizRXEftHq1ZEgsAtDria2DZrJT?= =?us-ascii?Q?KcBJa3R4xt/Mdo8wdjQGTWMWHDmQGI0Va09/XRi2ibqoqkb0H6BR8iNeWFaC?= =?us-ascii?Q?SHwxRHxqgLX0wkir7pYeCwGfpDQe5qiuiPsf/Rak5dp78gTySeRSlcoqgdDc?= =?us-ascii?Q?BVHjgBmi51CYj+FwgNNMUMw6xB6QkeJjjFz2RN/hq0usRRdu/i92JESessqW?= =?us-ascii?Q?q98Gn8vj5+ONmLhNcVWCpWR2M5vhiFK+UdaaMe69iUIvG9yHkOfTSoDeIKbp?= =?us-ascii?Q?rXCHu1/PZBpZJkR7u8PtjFwAzoXggUKYNT76TCIT6InOAwKMzzQSy0kLHkQn?= =?us-ascii?Q?G3khAiaXKaZ5EkWhdWPFxEljLFt0n+05Sy+Jg6ZHdA3xAO1aIXEMC4Y+Nwvo?= =?us-ascii?Q?tReGwJNHSWNZGH6EhkT9rlRb9tyznKBoFs9ZtzTjCvQxjXZCew1yBIwXQ5N9?= =?us-ascii?Q?acwRSHaP1HrA0h+1vkTGdzGQ26OZ9sbzl1+gB0IsXfIJWS/iRiR48l5oicLl?= =?us-ascii?Q?eWBMQXufvYBTrw4BYVi200dc/wxhGGKnWMdSCcZYTeF1dTyL65q/h9/XKB4l?= =?us-ascii?Q?+kjEABvNp+9HHXACzeOaTqPf33MmW3zjZvLmyDM4XU+NtyHYIE3+SSiCeKFQ?= =?us-ascii?Q?7mukkpGbRHoJSJShHq5yFtJnfO/hOCC1d2u3luJl?= X-MS-Exchange-CrossTenant-Network-Message-Id: 9f4ed383-a8c7-4a64-4b0b-08da90a27e13 X-MS-Exchange-CrossTenant-AuthSource: MN0PR11MB6206.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Sep 2022 07:28:00.2530 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 6oBA4SZRGH00/Wxw62BzdWDdXuCHERXpWTvwzTHhzj1ZbN09eMq49wxNM4AqlXMXBJQU+AuFAlT354fAFuQ5pA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR11MB3415 X-OriginatorOrg: intel.com X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mel, On 2022-09-06 at 10:57:17 +0100, Mel Gorman wrote: > On Mon, Sep 05, 2022 at 10:40:00PM +0800, Abel Wu wrote: > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > > index 6089251a4720..59b27a2ef465 100644 > > > --- a/kernel/sched/fair.c > > > +++ b/kernel/sched/fair.c > > > @@ -6427,21 +6427,36 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool > > > if (sd_share) { > > > /* because !--nr is the condition to stop scan */ > > > nr = READ_ONCE(sd_share->nr_idle_scan) + 1; > > > - /* overloaded LLC is unlikely to have idle cpu/core */ > > > - if (nr == 1) > > > - return -1; > > > + > > > + /* > > > + * Non-overloaded case: Scan full domain if there is > > > + * an idle core. Otherwise, scan for an idle > > > + * CPU based on nr_idle_scan > > > + * Overloaded case: Unlikely to have an idle CPU but > > > + * conduct a limited scan if there is potentially > > > + * an idle core. > > > + */ > > > + if (nr > 1) { > > > + if (has_idle_core) > > > + nr = sd->span_weight; > > > + } else { > > > + if (!has_idle_core) > > > + return -1; > > > + nr = 2; > > > + } > > > } > > > } > > > for_each_cpu_wrap(cpu, cpus, target + 1) { > > > + if (!--nr) > > > + break; > > > + > > > if (has_idle_core) { > > > i = select_idle_core(p, cpu, cpus, &idle_cpu); > > > if ((unsigned int)i < nr_cpumask_bits) > > > return i; > > > } else { > > > - if (!--nr) > > > - return -1; > > > idle_cpu = __select_idle_cpu(cpu, p); > > > if ((unsigned int)idle_cpu < nr_cpumask_bits) > > > break; > > > > I spent last few days testing this, with 3 variations (assume > > has_idle_core): > > > > a) full or limited (2cores) scan when !nr_idle_scan > > b) whether clear sds->has_idle_core when partial scan failed > > c) scale scan depth with load or not > > > > some observations: > > > > 1) It seems always bad if not clear sds->has_idle_core when > > partial scan fails. It is due to over partially scanned > > but still can not find an idle core. (Following ones are > > based on clearing has_idle_core even in partial scans.) > > > > Ok, that's rational. There will be corner cases where there was no idle > CPU near the target when there is an idle core far away but it would be > counter to the purpose of SIS_UTIL to care about that corner case. > > > 2) Unconditionally full scan when has_idle_core is not good > > for netperf_{udp,tcp} and tbench4. It is probably because > > the SIS success rate of these workloads is already high > > enough (netperf ~= 100%, tbench4 ~= 50%, compared to that > > hackbench ~= 3.5%) which negate a lot of the benefit full > > scan brings. > > > > That's also rational. For a single client/server on netperf, it's expected > that the SIS success rate is high and scanning is minimal. As the client > and server are sharing data on localhost and somewhat synchronous, it may > even partially benefit from SMT sharing. > Maybe off-topic, since we monitor the success rate and also other metrics for each optimization in SIS path, is it possible to merge your statistics patch [1] into upstream so we don't need to rebase in the future(although it is targeting kernel development)? Link: https://lore.kernel.org/lkml/20210726102247.21437-2-mgorman@techsingularity.net/ [cut] thanks, Chenyu