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 Kernel Packages, which is subscribed to linux-oem-5.14 in Ubuntu. https://bugs.launchpad.net/bugs/1956509 Title: Support AMD P-State cpufreq control mechanism Status in HWE Next: New Status in linux package in Ubuntu: In Progress Status in linux-oem-5.14 package in Ubuntu: Invalid Status in linux-oem-5.17 package in Ubuntu: In Progress Status in linux source package in Focal: Invalid Status in linux-oem-5.14 source package in Focal: In Progress Status in linux-oem-5.17 source package in Focal: Invalid Status in linux source package in Jammy: In Progress Status in linux-oem-5.14 source package in Jammy: Invalid Status in linux-oem-5.17 source package in Jammy: In Progress Bug description: [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 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 To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/1956509/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
