On 03.12.2024 09:11, Penny Zheng wrote: > amd-pstate 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_pstate CPPC has 2 operation modes: autonomous (active) mode, > and non-autonomous (passive) mode. We register different CPUFreq driver > for different modes, "amd-pstate" for passive mode and "amd-pstate-epp" > for active mode. > > The passive mode leverages common governors such as *ondemand*, > *performance*, etc, to manage the performance hints. And 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 > will 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-pstate is enabled with a top-level cpufreq=amd-pstate option. It will > fallback to cpufreq=xen if amd-pstate is unavailable. > > With `cpufreq=amd-pstate,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 2000000 KHz > Avg freq 2000000 KHz > Avg freq 2000000 KHz > Setting CPU in performance mode > Sampling and Outputs: > Avg freq 4640000 KHz > Avg freq 4220000 KHz > Avg freq 4640000 KHz > ``` > > Penny Zheng (11): > xen/x86: add CPPC feature flag for AMD processors > xen/x86: introduce new sub-hypercall to get CPPC data > xen/x86: introduce "cpufreq=amd-pstate" xen cmdline > xen/x86: get processor max speed from DMI table > xen/x86: introduce a new amd pstate driver for cpufreq scaling > xen/cpufreq: introduce policy type when cpufreq_driver->setpolicy > exists > xen/cpufreq: only set gov NULL when cpufreq_driver.target() exists > x86/cpufreq: add "cpufreq=amd-pstate,active" para > xen/x86: implement EPP support for the AMD processors > tools/xenpm: Print CPPC parameters for amd-pstate driver > xen/cpufreq: Adapt SET/GET_CPUFREQ_CPPC xen_sysctl_pm_op for > amd-pstate driver
Just to clarify: While certainly fine, it is a little surprising to see such a submission just after the submission deadline for 4.20 was passed. This is intended for 4.21 then, I expect? Or else have you talked to the release manager? Jan
