On 28.08.2025 12:02, Penny Zheng wrote: > amd-cppc is the AMD CPU performance scaling driver that introduces a > new CPU frequency control mechanism on modern AMD APU and CPU series in > Xen. The new mechanism is based on Collaborative Processor Performance > Control (CPPC) which provides finer grain frequency management than > legacy ACPI hardware P-States. Current AMD CPU/APU platforms are using > the ACPI P-states driver to manage CPU frequency and clocks with > switching only in 3 P-states. CPPC replaces the ACPI P-states controls > and allows a flexible, low-latency interface for Xen to directly > communicate the performance hints to hardware. > > amd_cppc driver has 2 operation modes: autonomous (active) mode, > and non-autonomous (passive) mode. We register different CPUFreq driver > for different modes, "amd-cppc" for passive mode and "amd-cppc-epp" > for active mode. > > The passive mode leverages common governors such as *ondemand*, > *performance*, etc, to manage the performance tuning. While the active mode > uses epp to provides a hint to the hardware if software wants to bias > toward performance (0x0) or energy efficiency (0xff). CPPC power algorithm > in hardware will automatically calculate the runtime workload and adjust the > realtime cpu cores frequency according to the power supply and thermal, core > voltage and some other hardware conditions. > > amd-cppc is enabled on passive mode with a top-level `cpufreq=amd-cppc` > option, > while users add extra `active` flag to select active mode. > > With `cpufreq=amd-cppc,active`, we did a 60s sampling test to see the CPU > frequency change, through tweaking the energy_perf preference from > `xenpm set-cpufreq-cppc powersave` to `xenpm set-cpufreq-cppc performance`. > The outputs are as follows: > ``` > Setting CPU in powersave mode > Sampling and Outputs: > Avg freq 580000 KHz > Avg freq 580000 KHz > Avg freq 580000 KHz > Setting CPU in performance mode > Sampling and Outputs: > Avg freq 4640000 KHz > Avg freq 4220000 KHz > Avg freq 4640000 KHz > ``` > > Penny Zheng (8): > xen/cpufreq: introduce new sub-hypercall to propagate CPPC data > xen/cpufreq: introduce "cpufreq=amd-cppc" xen cmdline and amd-cppc > driver > xen/cpufreq: implement amd-cppc driver for CPPC in passive mode > xen/cpufreq: implement amd-cppc-epp driver for CPPC in active mode > xen/cpufreq: get performance policy from governor set via xenpm > tools/cpufreq: extract CPPC para from cpufreq para > xen/cpufreq: bypass governor-related para for amd-cppc-epp > xen/cpufreq: Adapt SET/GET_CPUFREQ_CPPC xen_sysctl_pm_op for amd-cppc > driver
I'm somewhat confused by the submission: Both my mailbox and https://lists.xen.org/archives/html/xen-devel/2025-08/threads.html agree that cover letter and patch 1 were submitted twice, while patches 4 through 8 came through un-threaded. I can only assume that the duplicates are identical. Jan
