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client-ip=165.204.84.17; helo=SATLEXMB03.amd.com; pr=C Received: from SATLEXMB03.amd.com (165.204.84.17) by SJ1PEPF00002321.mail.protection.outlook.com (10.167.242.91) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8964.20 via Frontend Transport; Fri, 25 Jul 2025 05:13:10 +0000 Received: from SATLEXMB06.amd.com (10.181.40.147) by SATLEXMB03.amd.com (10.181.40.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Fri, 25 Jul 2025 00:13:07 -0500 Received: from SATLEXMB03.amd.com (10.181.40.144) by SATLEXMB06.amd.com (10.181.40.147) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Fri, 25 Jul 2025 00:13:07 -0500 Received: from [10.136.35.26] (10.180.168.240) by SATLEXMB03.amd.com (10.181.40.144) with Microsoft SMTP Server id 15.1.2507.39 via Frontend Transport; Fri, 25 Jul 2025 00:13:04 -0500 Message-ID: <72b7f683-0497-4fab-a05d-333ec5d2c309@amd.com> Date: Fri, 25 Jul 2025 10:43:03 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 01/12] sched/psi: Optimize psi_group_change() cpu_clock() usage To: , Peter Zijlstra CC: Chris Mason , , , , , , , , , Johannes Weiner , Beata Michalska References: <20250702114924.091581796@infradead.org> <20250702121158.350561696@infradead.org> <0d86c527-27a7-44d5-9ddc-f9a153f67b4d@meta.com> <20250716104050.GR1613200@noisy.programming.kicks-ass.net> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20250716104050.GR1613200@noisy.programming.kicks-ass.net> Content-Type: text/plain; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Jul 2025 05:13:10.5789 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: e0c2cfa8-85d9-4db0-3e19-08ddcb39f303 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=[SATLEXMB03.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF00002321.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CYYPR12MB8656 Hello Ingo, Peter, On 7/16/2025 4:10 PM, Peter Zijlstra wrote: > On Wed, Jul 16, 2025 at 08:53:01AM +0200, Beata Michalska wrote: >> Wouldn't it be enough to use SEQCNT_ZERO? Those are static per-cpu ones. > > Yeah, I suppose that should work. The below builds, but I've not yet > observed the issue myself. > > --- > Subject: sched/psi: Fix psi_seq initialization > From: Peter Zijlstra > Date: Tue, 15 Jul 2025 15:11:14 -0400 > > With the seqcount moved out of the group into a global psi_seq, > re-initializing the seqcount on group creation is causing seqcount > corruption. > > Fixes: 570c8efd5eb7 ("sched/psi: Optimize psi_group_change() cpu_clock() usage") > Reported-by: Chris Mason > Suggested-by: Beata Michalska > Signed-off-by: Peter Zijlstra (Intel) I've been running with this fix for a bunch of my testing and when I forget about it (as was the case when testing John's Proxy Exec branch), I usually run into the softlockup in psi_avgs_work(). Is it too late to include this in tip:sched/core for v6.17? Also feel free to include: Tested-by: K Prateek Nayak -- Thanks and Regards, Prateek