Hello, I am experiencing a significant performance degradation after upgrading my kernel from version 6.6 to 6.8 and would appreciate any insights or suggestions. I am running a high-load simulation system that spawns more than 1000 threads and the overall CPU usage is 30%+ . Most of the threads are using real-time scheduling (SCHED_RR), and the threads of a model are using SCHED_DEADLINE. After upgrading the kernel, I noticed that the execution time of my model has increased from 4.5ms to 6ms. What I Have Done So Far: 1. I found this [bug report](https://bugzilla.kernel.org/show_bug.cgi?id=219366#c7) and reverted the commit efa7df3e3bb5da8e6abbe37727417f32a37fba47 mentioned in the post. Unfortunately, this did not resolve the issue. 2. I performed a git bisect and found that after these two commits related to scheduling (RT and deadline) were merged, the problem happened. They are 612f769edd06a6e42f7cd72425488e68ddaeef0a, 5fe7765997b139e2d922b58359dea181efe618f9 After reverting these two commits, the model execution time improved to around 5 ms. 3. I revert two more commits, and the execution time is back to 4.7ms: 63ba8422f876e32ee564ea95da9a7313b13ff0a1, efa7df3e3bb5da8e6abbe37727417f32a37fba47 My questions are: 1.Has anyone else experienced similar performance degradation after upgrading to kernel 6.8? 2.Can anyone explain why these two commits are causing the problem? I am not very familiar with the kernel code and would appreciate any insights. 3.Are there any additional settings or configurations I need to apply when using kernel 6.8 to avoid this issue? My CPU is AMD Ryzen Threadripper 3970X, and my desktop uses Ubuntu 24.04. Thanks again for any insights or suggestions. Please let me know if any other information is needed. Best, Chenbo -- This email and any relevant attachments may include confidential and/or proprietary information. Any distribution or use by anyone other than the intended recipient(s) or other than for the intended purpose(s) is prohibited and may be unlawful. If you are not the intended recipient of this message, please notify the sender by replying to this message and then delete it from your system.
