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Tue, 7 Jul 2026 14:51:28 +0000 Message-ID: <8d5d9c98-54df-44fe-8795-189554ea2399@intel.com> Date: Tue, 7 Jul 2026 07:51:26 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/3] arm_mpam: resctrl: Add pass-through resctrl_arch_preconvert_bw() To: Ben Horgan CC: , , , , , , , , , , , , References: <20260706160639.2136674-1-ben.horgan@arm.com> <20260706160639.2136674-3-ben.horgan@arm.com> <4c520a28-9a72-4abd-8e5b-654a312c92fd@intel.com> Content-Language: en-US From: Reinette Chatre In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR03CA0167.namprd03.prod.outlook.com (2603:10b6:303:8d::22) To SJ2PR11MB8370.namprd11.prod.outlook.com (2603:10b6:a03:540::20) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ2PR11MB8370:EE_|SN7PR11MB7975:EE_ X-MS-Office365-Filtering-Correlation-Id: affa975f-7d9f-4065-96ec-08dedc3739e7 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|7416014|1800799024|23010399003|4143699003|22082099003|18002099003|3023799007|56012099006|11063799006; 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As >>> MPAM uses a binary fixed point fraction format for MBA rather than a >>> decimal percentage, this introduces rounding errors. >>> >>> Without this additional rounding, if the user reads the value in an MB >>> schema and then writes it back to the schema, the value in hardware won't >>> change. However, with this additional rounding, this guarantee is broken >>> for systems with mbw_wd < 7. >>> >>> resctrl is introducing resctrl_arch_preconvert_bw() to allow the arch code >>> to specify the conversion resctrl does to the user-provided bandwidth >>> value. Add the MPAM version of resctrl_arch_preconvert_bw(). This does no >>> conversion. >>> >>> Signed-off-by: Ben Horgan >>> Reviewed-by: Reinette Chatre >>> >> >> Unfortunately the "---" separator is missing here. > > Another silly mistake.. sorry about that. I've corrected locally and > will send a respin in a day or two. No problem. When you respin, could you please add a snippet to the cover about expectations how this series should be merged? This will be the first piece of work that touches the x86 and Arm driver as well as resctrl fs code. So far I assumed it will go in via tip but I think it will help to state this from Arm side. We still need a plan for if/when the Arm side touches the same code though. Thankfully this work is small. Reinette