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15.20.8901.018; Fri, 4 Jul 2025 20:33:51 +0000 Message-ID: <25673be5-e83f-419d-9066-336ecb32ba3d@windriver.com> Date: Fri, 4 Jul 2025 14:32:51 -0600 User-Agent: Mozilla Thunderbird Content-Language: en-US To: linux-rt-users@vger.kernel.org From: Chris Friesen Subject: question about semantics of RT mutexes and RT throttling Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BLAP220CA0008.NAMP220.PROD.OUTLOOK.COM (2603:10b6:208:32c::13) To DS7PR11MB8806.namprd11.prod.outlook.com (2603:10b6:8:253::19) Precedence: bulk X-Mailing-List: linux-rt-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR11MB8806:EE_|MW3PR11MB4652:EE_ X-MS-Office365-Filtering-Correlation-Id: 3367169f-72c2-4e91-e698-08ddbb3a1651 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|1800799024; 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a=wKuvFiaSGQ0qltdbU6+NXLB8nM8=:19 a=Ol13hO9ccFRV9qXi2t6ftBPywas=:19 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=Wb1JkmetP80A:10 a=PWlMuy4nkWDbdMFYZewA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: PCBXekZMBgm9OqCGKYnuysi2Pk0Ft6kX X-Proofpoint-ORIG-GUID: PCBXekZMBgm9OqCGKYnuysi2Pk0Ft6kX X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.7,FMLib:17.12.80.40 definitions=2025-07-04_06,2025-07-04_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 clxscore=1031 priorityscore=1501 adultscore=0 spamscore=0 mlxscore=0 lowpriorityscore=0 mlxlogscore=593 malwarescore=0 suspectscore=0 impostorscore=0 bulkscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.21.0-2505280000 definitions=main-2507040155 Hi all, Just wondering, with PREEMPT_RT on the 6.6 kernel (and I'm curious about the 6.12 kernel as well), if a realtime-priority task is on the waiter list for a mutex, and RT throttling kicks in, are non-RT tasks able to acquire the mutex? Or does the RT task acquire the mutex even though it's supposed to be throttled? Or does nobody acquire the mutex until RT throttling ends? Just wondering if RT throttling helps at all if multiple RT tasks are contending on a mutex at the same time as non-RT tasks? Thanks, Chris