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Shenoy" , Aubrey Li , Qais Yousef , Juri Lelli , Rik van Riel , Yicong Yang , Barry Song <21cnbao@gmail.com>, Subject: Re: [PATCH v6 3/4] sched/fair: Introduce SIS_CORE Message-ID: References: <20221019122859.18399-1-wuyun.abel@bytedance.com> <20221019122859.18399-4-wuyun.abel@bytedance.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20221019122859.18399-4-wuyun.abel@bytedance.com> X-ClientProxiedBy: SG2PR02CA0131.apcprd02.prod.outlook.com (2603:1096:4:188::6) To MN0PR11MB6206.namprd11.prod.outlook.com (2603:10b6:208:3c6::8) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN0PR11MB6206:EE_|SJ0PR11MB5582:EE_ X-MS-Office365-Filtering-Correlation-Id: 65018fd9-08a9-4e94-93eb-08dab31935dc 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:(13230022)(7916004)(346002)(136003)(366004)(39860400002)(376002)(396003)(451199015)(41300700001)(6486002)(83380400001)(82960400001)(7416002)(5660300002)(86362001)(2906002)(186003)(4001150100001)(8936002)(8676002)(6916009)(53546011)(26005)(6506007)(6512007)(316002)(66946007)(6666004)(38100700002)(4326008)(9686003)(66556008)(33716001)(66476007)(54906003)(478600001);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?yWhbgah2FochbUiPbc2cuOUEQMT9SV9s32kLyg+LMPB2b8PaPkdj7GtzT6vh?= =?us-ascii?Q?DRb1MCj0w9TzNCQAIz3SHbW7flr0a0/o12HqGQVMaxzFmBa88CDLiJBQ5jhy?= =?us-ascii?Q?Ep7+VBWXpFWp5GnOtMLMm0IxQRep1TVt5+EOaojVhceMWdns9jWHIvq/YrpW?= =?us-ascii?Q?odOND7i7qrtKTC/Ujt0aa9k8kd3enmF7LOyQEraq2AMj7kyDq7wjU+hIuEG6?= =?us-ascii?Q?xe+b8Q5lCE+T/7gEVoX8Vqht9osgd/eC2vZ7TbpdGHz9EfQbfkedFmQdL+ZQ?= =?us-ascii?Q?sMjSwtsWb/UWw38RUX93Vbny1d4A7slb4zVuJW2OGd3v1i7fDc0XyjZF1l1c?= =?us-ascii?Q?8qnNLGonEg/7T7+PDCmq6TVnzGQUPjgyPWfVAuM8GOgvT6i2tfkveXlRglId?= =?us-ascii?Q?EmdShFFvQpzfhiNdsCQ8A4sJsAfdMB2+cWjAm9frBGB84KAdXWj6JPPrC31p?= =?us-ascii?Q?nRvoqmc7DVHQacfU716ZBcpgD3NwcwccLfoXo9RXPRyDdShRufHlJ7inHl88?= =?us-ascii?Q?HvpA1j3FSWKD/G+dgfFGFYVP1myTpZx1AG5VaJGYhVGfaXtZJ3FyV9TXTu0T?= =?us-ascii?Q?6QKwpUtYuca8euRMt6tXbtKcDDSCeq7RPoCSMzUVksQkhxO312BbKCk3ncfo?= =?us-ascii?Q?YWzHogmm8AGP7VQaeWZppZmRSdQS8TlR+V5rfCdTF7a87K1Mjr1FSZZTY6Q6?= =?us-ascii?Q?9gpFmKlTyS9j0GhnCvk0SSKUAfCqSz0tR2RLiVdSuYJPDlv92M30D9pxvRvq?= =?us-ascii?Q?cCmlplGL7gw85+mtvSUR+C9bb0hOdZzNS4FlFgLOfsat1CoeTg584T4hsy67?= =?us-ascii?Q?Yp9OMIYRV7LJdvPmoFYmCWJCPEvA+KdPUqkT4heMXtyE41DLcOY9+BXtHllA?= =?us-ascii?Q?i3IWhEA/l5mjVJqeDjs93w+dvc3etZaub6jFW+p6qYxE/Q8vJI15yQhqsfZZ?= =?us-ascii?Q?hU9LzzKVboosUI1d+VCiD4lckDo78FrPeODbgRCqBnx/W1GfAACo0iToFsbB?= =?us-ascii?Q?1hkVGgFAnYyNs+jbLSNDIkJuJi6azMOJgz3t7BJHQW8o9BrL0IlXlAEo9KYJ?= =?us-ascii?Q?vtc9dZ8/p9eLyb/1Os9mJK2Xq6jQJDTZ98UdF2mH3bBeoSP322hobF0rKixz?= =?us-ascii?Q?N+L9ELLuDlbDd1E/mqISQS9bJ3JYfHwaiq5Ptz+hKVdDRsWqaQjQSAyCl8ll?= =?us-ascii?Q?QsmfgdETclU+n9vbAa/O81pBlI4R3mbAMI/8cF/kAxS6kg3qHwo2cBjGFayo?= =?us-ascii?Q?HLrBDYm27oriygNnqUuNMj5fLs0mbWAbABcgIDOFl7Rm9mOezAuMBEyuYHcB?= =?us-ascii?Q?Sy7YkzpbUWuCa/TE5oWVoSUd/CrsEO1f+BGfqDWeyw2xfDXXsg5KW+AbtlnW?= =?us-ascii?Q?jjlFm/Qcm2cCVJP7KEVjmmImaGP63gcV8wtYd/lFkV+F/Ok5kE47PuThpnRl?= =?us-ascii?Q?zd5MnUqhIbcjKx6tY5sjatUed9zXjepkFzwdrdI4qvz8a6fNE7Oe2U1Hj97A?= =?us-ascii?Q?f8UZ0hcP0mCtYk6kDJjsQzfkuawclbc4wozEcEj/3xPatpK3zXGu+uogBFJS?= =?us-ascii?Q?d3jvdOOy9oSTwCxl6T4Nfzy/WVdj1rpUBUYmCdjq?= X-MS-Exchange-CrossTenant-Network-Message-Id: 65018fd9-08a9-4e94-93eb-08dab31935dc X-MS-Exchange-CrossTenant-AuthSource: MN0PR11MB6206.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Oct 2022 04:03:28.7579 (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: RbIXT4XK6Cvlkj045mBW2+R3isDZPc8PcXXLwH4S8KYNMdqOtsLqFRiZXS03qe8g8AMgtz/nr9sUWI6zAkWKuw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR11MB5582 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022-10-19 at 20:28:58 +0800, Abel Wu wrote: [cut] > A major concern is the accuracy of the idle cpumask. A cpu present > in the mask might not be idle any more, which is called the false > positive cpu. Such cpus will negate lots of benefit this feature > brings. The strategy against the false positives will be introduced > in next patch. > I was thinking that, if patch[3/4] needs [4/4] to fix the false positives, maybe SIS_CORE could be disabled by default in 3/4 but enabled in 4/4? So this might facilicate git bisect in case of any regression check? [cut] > + * To honor the rule of CORE granule update, set this cpu to the LLC idle > + * cpumask only if there is no cpu of this core showed up in the cpumask. > + */ > +static void update_idle_cpu(int cpu) > +{ > + struct sched_domain_shared *sds; > + > + if (!sched_feat(SIS_CORE)) > + return; > + > + sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); > + if (sds) { > + struct cpumask *icpus = to_cpumask(sds->icpus); > + > + /* > + * This is racy against clearing in select_idle_cpu(), > + * and can lead to idle cpus miss the chance to be set to > + * the idle cpumask, thus the idle cpus are temporarily > + * out of reach in SIS domain scan. But it should be rare > + * and we still have ILB to kick them working. > + */ > + if (!cpumask_intersects(cpu_smt_mask(cpu), icpus)) > + cpumask_set_cpu(cpu, icpus); Maybe I miss something, here we only set one CPU in the icpus, but when we reach update_idle_cpu(), all SMT siblings of 'cpu' are idle, is this intended for 'CORE granule update'? thanks, Chenyu