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charset="us-ascii" Content-ID: <5C3220BB1279BE4EA63CEBA5172FFCD5@namprd12.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: DS0PR12MB8442.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: e632dc8b-7cbd-4f51-3956-08dea7186704 X-MS-Exchange-CrossTenant-originalarrivaltime: 01 May 2026 00:27:18.2270 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: M3SGhK6FDB1HseCQeKlHjgDsm/2L/JjqMDGNW3AbVzUpXLjV6U7uF+ZqBAGDAoxDQEak/43eAHmFy+5CUzikjw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV8PR12MB9449 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260430_172727_266079_8106A2D9 X-CRM114-Status: GOOD ( 11.47 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > On Apr 29, 2026, at 16:56, Besar Wicaksono wrote: >=20 > PMCCNTR_EL0 may continue to increment on NVIDIA Olympus CPUs while the > PE is in WFI/WFE. That does not necessarily match the CPU_CYCLES event > counted by a programmable counter, so using PMCCNTR_EL0 for cycles can > give results that differ from the programmable counter path. >=20 > Extend the existing PMCCNTR avoidance decision from the SMT case to > also cover Olympus. Store the result in the common arm_pmu state at > registration time, so arm_pmuv3 can keep using a single flag when > deciding whether CPU_CYCLES may use PMCCNTR_EL0. >=20 > Use the cached MIDR from cpu_data to identify Olympus parts and avoid > reading MIDR_EL1 in the event path. >=20 > Signed-off-by: Besar Wicaksono Verified on NVIDIA Vera (Olympus CPUs) with UEFI SMT disabled. Confirmed that grouped cpu_cycles events show ~1x ratio (both on programmable counters) with the patch vs ~15x inflation without it. Tested-by: Matthew R. Ochs