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Thu, 26 Mar 2020 16:32:54 +0000 Subject: Re: [PATCH v2] isolcpus: affine kernel threads to specified cpumask To: Frederic Weisbecker , David Laight Cc: 'Marcelo Tosatti' , Thomas Gleixner , "linux-kernel@vger.kernel.org" , Christoph Lameter , Jim Somerville , Andrew Morton , Frederic Weisbecker , Peter Zijlstra References: <20200323135414.GA28634@fuller.cnet> <87k13boxcn.fsf@nanos.tec.linutronix.de> <87imiuq0cg.fsf@nanos.tec.linutronix.de> <20200324152016.GA25422@fuller.cnet> <20200326162218.GB3946@lenoir> From: Chris Friesen Message-ID: <76fa0270-40c5-aac7-1c53-38384fa3467d@windriver.com> Date: Thu, 26 Mar 2020 10:32:51 -0600 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 In-Reply-To: <20200326162218.GB3946@lenoir> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BY5PR13CA0007.namprd13.prod.outlook.com (2603:10b6:a03:180::20) To BYAPR11MB3271.namprd11.prod.outlook.com (2603:10b6:a03:7b::26) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [172.25.39.6] (70.64.94.148) by BY5PR13CA0007.namprd13.prod.outlook.com (2603:10b6:a03:180::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2878.9 via Frontend Transport; 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X-Microsoft-Antispam-Message-Info: E72LHfN697r0iG2jwT1gldutWHGDyuoxu3STbtrQTRwhoi/97KENrAkxXeaqCYLdRpoyNdWQOBvrLB3AI33tXjkMqyfB1Eld4D6lWBiaW8gVX/dLXoDY+V/iN5bxzEStJaEP/zYbn/Cvmlh5Uy15MPrwb8J+8+DPLai8NqARDbx9HdFWKQCnTOpQzG/7olu7/uYtmbWpCSq+5QA4ReKhvOhbsLSKvceUM82xa26OaPp6V5e5CDp+aIm1hFq4BNXnEyavi9s0TzMCCYwdoCf1d0jnSUH2ad6xwiXu608Bxu0zwxLh3NgWQI+9SeghRlrYufzfRRn4mqVyXomGiEWp4dqLuxhe/n/XWI2HxUqGlA+Wd/nSqfXXzH4NajZZumEKQYqiJSTn94pqjbUk1K9ZRGa6zZN7XYnlVt79cbmvHT7Sp7LaSU45f27FTfcIJD/F X-MS-Exchange-AntiSpam-MessageData: xXXv3iOLLx8E6SPN99jnqYL+GjZ4bAFD8964Us5qaW3konAsoFf3pwA5P1n1yyPBKaUlGoidhlV7jKs8PEOMD3vMQpoP9fRT4807yBExnv8xaCiDh8JHA9M+ijJtRmgDxU8921LEshkvCzeGwoDoeA== X-OriginatorOrg: windriver.com X-MS-Exchange-CrossTenant-Network-Message-Id: f246097c-07ee-466b-a505-08d7d1a3556c X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Mar 2020 16:32:54.2060 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ddb2873-a1ad-4a18-ae4e-4644631433be X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: O3UT7lAItltVdsnBuB1eWYn3yWrT47j7ZP/uQeL17L19LQ8COKNGE1mmlli1p+EEJUqVG1kBARREGsvc65iLZTw59TnSofg7hOEEJbkiqbY= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR11MB3573 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/26/2020 10:22 AM, Frederic Weisbecker wrote: > On Wed, Mar 25, 2020 at 06:05:27PM +0000, David Laight wrote: >> How about making it possible to change the default affinity >> for new kthreads at run time? >> Is it possible to change the affinity of existing threads? >> Or maybe only those that didn't specify an explicit one?? > > That's already possible yes, most unbound kthreads are accessible > through /proc including kthreadd from which new kthread will inherit > their CPU affinity. Are you sure that the new kthread will inherit the CPU affinity? __kthread_create_on_node() explicitly sets the new thread as SCHED_NORMAL with a mask of "cpu_all_mask". Chris