SRU: * https://lists.ubuntu.com/archives/kernel-team/2022-April/129288.html (oem-5.14, jammy) * https://lists.ubuntu.com/archives/kernel-team/2022-April/129307.html (oem-5.17, unstable)
** Description changed: - https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux- - pm.git/commit/?h=linux-next&id=40181d67f1e9f1ac87af9c0c194e40ab2a081974 + [SRU Justification] + + [Impact] + + AMD P-State CPU performance scaling driver not yet supported on AMD Zen + based CPU series. + + [Fix] + + Mainline commits starting at commit d341db8f48ea ("x86/cpufeatures: Add + AMD Collaborative Processor Performance Control feature flag") from v5.17. + + Even this committed, the defconfig will build it as module, and that + prevents AMD P-State driver from actually taking effect. Therefore an + additional fix to the kernel configs is necessary. + + [Test Case] $ sudo cpupower frequency-info analyzing CPU 0: driver: amd-pstate CPUs which run at the same hardware frequency: 0 CPUs which need to have their frequency coordinated by software: 0 maximum transition latency: 131 us hardware limits: 400 MHz - 3.10 GHz - available cpufreq governors: conservative ondemand userspace powersave performance schedutil + available cpufreq governors: conservative ondemand userspace powersave + performance schedutil current policy: frequency should be within 1.60 GHz and 3.10 GHz. The governor "ondemand" may decide which speed to use within this range. current CPU frequency: Unable to call hardware current CPU frequency: 1.59 GHz (asserted by call to kernel) boost state support: Supported: yes Active: yes Boost States: 0 Total States: 3 Pstate-P0: 3100MHz Pstate-P1: 1800MHz Pstate-P2: 1600MHz + + [Where problems could occur] + + The CPPC feature is implemented in two ways depending on underlying HW + details for the APU/CPU: + * Dedicated MSR + * Shared memory + + The metrics used to measure power/performance efficiency don't show any + improvement on the designs that use shared memory. They do show + improvements in the MSR designs. + + So the code will only enable it by default on the MSR implementation. + + [Other Info] + + Althought the v5.17 kernel and newer should have already this committed, + an additional fix to the kernel configs is necessary, and + unstable/oem-5.17 are also nominated (in a separate thread for they don't + need other parts but the config). + + ========== original bug report ========== + + https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux- + pm.git/commit/?h=linux-next&id=40181d67f1e9f1ac87af9c0c194e40ab2a081974 + + $ sudo cpupower frequency-info + analyzing CPU 0: + driver: amd-pstate + CPUs which run at the same hardware frequency: 0 + CPUs which need to have their frequency coordinated by software: 0 + maximum transition latency: 131 us + hardware limits: 400 MHz - 3.10 GHz + available cpufreq governors: conservative ondemand userspace powersave performance schedutil + current policy: frequency should be within 1.60 GHz and 3.10 GHz. + The governor "ondemand" may decide which speed to use + within this range. + current CPU frequency: Unable to call hardware + current CPU frequency: 1.59 GHz (asserted by call to kernel) + boost state support: + Supported: yes + Active: yes + Boost States: 0 + Total States: 3 + Pstate-P0: 3100MHz + Pstate-P1: 1800MHz + Pstate-P2: 1600MHz -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1956509 Title: Support AMD P-State cpufreq control mechanism To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/1956509/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
