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client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by BL02EPF0001A0FE.mail.protection.outlook.com (10.167.242.105) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8901.15 via Frontend Transport; Wed, 9 Jul 2025 09:21:11 +0000 Received: from spgblr-titan-01.amd.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Wed, 9 Jul 2025 04:21:07 -0500 From: Nikhil Dhama To: CC: , , , , , , , , , Subject: Re: [linus:master] [mm] c544a952ba: netperf.Throughput_Mbps 18.9% Date: Wed, 9 Jul 2025 14:50:46 +0530 Message-ID: <20250709092046.10428-1-nikhil.dhama@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <202507030638.d8cff1fb-lkp@intel.com> References: <202507030638.d8cff1fb-lkp@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL02EPF0001A0FE:EE_|SN7PR12MB7372:EE_ X-MS-Office365-Filtering-Correlation-Id: dd0060fd-965c-4af6-6437-08ddbec9f1f1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|82310400026|36860700013|1800799024|13003099007; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Jul 2025 09:21:11.2867 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: dd0060fd-965c-4af6-6437-08ddbec9f1f1 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=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL02EPF0001A0FE.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB7372 Hi, On 7/3/2025 11:19 AM, kernel test robot wrote: > > Hello, > > > we reported > "[linus:master] [mm] c544a952ba: vm-scalability.throughput 33.3% improvement" > in > https://lore.kernel.org/all/202506121415.eeceda1d-lkp@intel.com/ > > now we captured a netperf regression on a Core machine. > > we don't have enough knowledge if this is a tradeoff, just make out this report > FYI. > > > kernel test robot noticed a 18.9% regression of netperf.Throughput_Mbps on: > [...] > The kernel config and materials to reproduce are available at: > https://download.01.org/0day-ci/archive/20250703/202507030638.d8cff1fb-lkp@intel.com I tried reproducing this issue using the shared kernel config, On a 192 cores AMD EPYC server with 768G memory, I am getting following score (normalised wrt v6.15 vanilla): netperf UDP_STREAM ------------------ v6.15 vanilla 100 v6.15 with (c544a952ba) 100.085 > commit: c544a952ba61b1a025455098033c17e0573ab085 ("mm: pcp: increase pcp->free_count threshold to trigger free_high") > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master > > [still regression on linus/master 66701750d5565c574af42bef0b789ce0203e3071] > [still regression on linux-next/master 3f804361f3b9af33e00b90ec9cb5afcc96831e60] > > testcase: netperf > config: x86_64-rhel-9.4 > compiler: gcc-12 > test machine: 4 threads Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz (Skylake) with 32G memory > parameters: > > ip: ipv4 > runtime: 300s > nr_threads: 1 > cluster: cs-localhost > test: UDP_STREAM > cpufreq_governor: performance To match thread count and memory, On the same machine I disabled all cpus keeping only 4 of them enabled, and limited memory to 32G. with this configuration, I am getting the following score: netperf UDP_STREAM ------------------ v6.15 vanilla 100 v6.15 with (c544a952ba) 154 I am not able to repoduce the issue, am I missing something which is required to reproduce? Thanks, Nikhil