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Wed, 15 Apr 2026 15:38:51 +0000 Message-ID: <0892e8ed-e903-44c9-b0cc-4c4b52cd4fc8@intel.com> Date: Wed, 15 Apr 2026 08:38:49 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 5/7] fs/resctrl: Continue counter allocation after failure To: Ben Horgan , CC: , , , , , , , , , , , References: <20260326172551.1553871-1-ben.horgan@arm.com> <20260326172551.1553871-6-ben.horgan@arm.com> <82ff4c2a-88fb-4e87-a30e-3c00fe8b3025@arm.com> <350ba3f7-ae0a-4092-bea3-0a9b62deabb4@intel.com> <96d85349-4e8b-4a22-b31d-06f89685f076@arm.com> Content-Language: en-US From: Reinette Chatre In-Reply-To: <96d85349-4e8b-4a22-b31d-06f89685f076@arm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR03CA0238.namprd03.prod.outlook.com (2603:10b6:303:b9::33) To SJ2PR11MB7573.namprd11.prod.outlook.com (2603:10b6:a03:4d2::10) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ2PR11MB7573:EE_|CYXPR11MB8692:EE_ X-MS-Office365-Filtering-Correlation-Id: 159d9cc8-45be-4709-8a10-08de9b0517fc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|366016|1800799024|56012099003|22082099003|18002099003; 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As counters are limited, such allocation may fail and >>>> when it does counter allocations for the remaining domains are >>>> skipped even if the domains have available counters. >>>> >>>> Since a counter allocation failure may result in counter allocation >>>> skipped on other domains the user needs to view the resource group's >>> >>> skipped -> being skipped >>> >>>> mbm_L3_assignments files to get an accurate view of counter assignment >>>> in a new resource group and then manually create counters in the skipped >>>> domains with available counters. >>>> >>>> Writes to mbm_L3_assignments using the wildcard format, :*=e, >>>> also skip counter allocation in other domains after a counter allocation >>>> failure. >>>> >>>> When handling a request to create counters in all domains it is unnecessary >>>> for a counter allocation in one domain to prevent counter allocation in >>>> other domains. Always attempt to allocate all the counters requested. >>> >>> I can use this but how about if I add, >>> >>> Skipping counter allocation in subsequent domains after failure makes predicting which >>> counters will be allocated harder for the user as they need to know the ordering of the >>> domains as well as the expected failures. >> >> I do not see why the user needs to make any predictions with the current implementation. >> mbm_L3_assignments will always contain accurate information regarding counter assignment, no? > > They can see the result with mbm_L3_assignments. In general, if the user is doing any operation it helps for them to > know what they can expect from that operation before doing it. I totally agree. I seem to be missing the goal here. Are you saying that currently it is not clear what the user can expect when running these commands? I believe that is clarified with the documentation update in patch #6? > > Happy to drop the extra sentence if you don't think it adds anything. Making all allocations of multiple counters best > effort is the main point. I do not object adding extra sentences but the proposal mentions how user space needs to predict behaviors and know about kernel internals which I do not believe is required now nor with planned changes. I really seem to be missing something here so would appreciate if you could elaborate the goals here. Reinette