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Mon, 6 Jul 2026 21:33:30 +0000 Message-ID: <4c520a28-9a72-4abd-8e5b-654a312c92fd@intel.com> Date: Mon, 6 Jul 2026 14:33:29 -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> Content-Language: en-US From: Reinette Chatre In-Reply-To: <20260706160639.2136674-3-ben.horgan@arm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR03CA0202.namprd03.prod.outlook.com (2603:10b6:303:b8::27) To SJ2PR11MB8370.namprd11.prod.outlook.com (2603:10b6:a03:540::20) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ2PR11MB8370:EE_|BL1PR11MB5317:EE_ X-MS-Office365-Filtering-Correlation-Id: 83f5763c-e980-4509-39a9-08dedba6394c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|366016|1800799024|7416014|376014|3023799007|11063799006|56012099006|4143699003|22082099003|18002099003; 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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. > Changes since v3: > Parameter order switch (Reinette) > Add Reinette's R-b > --- Reinette