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Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by CY8PEPF00000054.mail.protection.outlook.com (10.167.247.58) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.615.4 via Frontend Transport; Thu, 12 Nov 2026 11:09:31 +0000 Received: from satlexmb08.amd.com (10.181.42.217) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.53; Thu, 12 Nov 2026 05:09:31 -0600 Received: from [192.168.0.101] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.53 via Frontend Transport; Thu, 12 Nov 2026 05:09:25 -0600 Message-ID: <3b28aa06-1496-42b1-b1d2-c654c7a1ff0c@amd.com> Date: Thu, 12 Nov 2026 16:39:23 +0530 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC] perf/x86/amd/lbr: Don't freeze the LBR on PMI for user-only filters To: Andrii Nakryiko , Puranjay Mohan CC: Sandipan Das , , , Peter Zijlstra , "Ingo Molnar" , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , "Thomas Gleixner" , Borislav Petkov , Dave Hansen , , "H . Peter Anvin" , Andrii Nakryiko , Ravi Bangoria References: <20261105170340.165507-1-puranjay@kernel.org> Content-Language: en-US From: Ravi Bangoria In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY8PEPF00000054:EE_|IA0PR12MB7774:EE_ X-MS-Office365-Filtering-Correlation-Id: 33b0c68d-b61d-40c9-8756-08df40ad6d71 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|36860700016|7416014|376014|1800799024|82310400026|11063799006|4143699003|261102123227099003|261021121427099003|261022075727099003|261026121527099003|56012099006|22082099003|18002099003|6133799003|10067099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb08.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(23010399003)(36860700016)(7416014)(376014)(1800799024)(82310400026)(11063799006)(4143699003)(261102123227099003)(261021121427099003)(261022075727099003)(261026121527099003)(56012099006)(22082099003)(18002099003)(6133799003)(10067099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: ZKDkwyYFUBb53RphUrwfisUDW5rPEnK7AnbQqBMx8EqAM8HX3eoH9tsBKZXZjnDJEpr5Lc5MlpKuKoswmRziXP0zgrpRjRx49Zyfy3HAdR9BHi30WqxZ1GCjc0chBby+IYCopjBumh0gO9cvo4fWIN+vsvVhZfSfG4+Bsk+ChxWa50i/OI/D06Fva38g8lb6bH7H+/h4zBuEQlr0Ykh5qTTCTQI0R30tVNHhc/JkoFNO+o0KrjwsQxVoffh/IuA43vyFotzb+vVDjhyymxEjmXcW6NfiKEDJO80+oZub+6wH4lSjrsgCrOu1d0Xu+i9d5DjX6IBd5CgLIdRx+tkmv4STBimIGmOpxPBCL5egoRCQmx0RMSUSpIcKZy00b8qeE6fO0ZfQOQDvAbqwHTkVSpR/QP/dKr6gSk8HY8tN4zRuBfiaLS9+2r6LB0HZ+xXP X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Nov 2026 11:09:31.8694 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 33b0c68d-b61d-40c9-8756-08df40ad6d71 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CY8PEPF00000054.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR12MB7774 Puranjay, Andrii, >> heh, so we basically either >> >> a) opt-in freeze with *new config*, but do it *only for non-kernel LBR* >> >> or >> >> b) opt-out freeze *only for non-kernel LBR* _unconditionally_, but >> without adding any new config >> >> In both cases we have a behavior that makes sense in practice, but a) >> adds some new config, while b) doesn't add anything. End result is the >> same, just more configuration and need to change user space code to >> opt-out the freeze. >> >> Is a) worth it, or we should stick to b) and keep it simple, Sandipan? Have you run a PGO experiment with the patch, and does it show a benefit? Also, have you seen any regression in any benchmarks? If no-freeze regresses some of them, we may need to give the user an option to keep the freeze enabled. No? Thanks, Ravi