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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by BL6PEPF0002256E.mail.protection.outlook.com (10.167.249.36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9434.6 via Frontend Transport; Tue, 16 Dec 2025 04:42:44 +0000 Received: from satlexmb08.amd.com (10.181.42.217) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Mon, 15 Dec 2025 22:42:41 -0600 Received: from [10.136.36.160] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Mon, 15 Dec 2025 22:42:36 -0600 Message-ID: Date: Tue, 16 Dec 2025 10:12:35 +0530 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Patch v5 00/19] Support SIMD/eGPRs/SSP registers sampling for perf To: Dapeng Mi CC: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Dave Hansen , Ian Rogers , Adrian Hunter , Jiri Olsa , Alexander Shishkin , Andi Kleen , Eranian Stephane , Mark Rutland , , , , Zide Chen , "Falcon Thomas" , Dapeng Mi , "Xudong Hao" , Ravi Bangoria References: <20251203065500.2597594-1-dapeng1.mi@linux.intel.com> Content-Language: en-US From: Ravi Bangoria In-Reply-To: <20251203065500.2597594-1-dapeng1.mi@linux.intel.com> Content-Type: text/plain; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Dec 2025 04:42:44.5472 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a7914af6-8a51-4ded-12b4-08de3c5d8e0b 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF0002256E.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB8342 Hi Dapeng, > While the hardware solution remains preferable due to its lower > overhead and higher accuracy, this software approach provides a > viable alternative. Lower accuracy in the software approach is due to the delay in an NMI delivery which will make the SIMD data misaligned a bit? Something like: insn1 insn2 -> Overflow. RIP, GPRs captured by PEBS and NMI triggered insn3 insn4 insn5 -> NMI delivered here, so SIMD regs are captured here? insn6 Am I interpreting it correctly? Thanks, Ravi