[AMD Official Use Only - AMD Internal Distribution Only] Hi,
> -----Original Message----- > From: Jan Beulich <jbeul...@suse.com> > Sent: Tuesday, December 3, 2024 5:01 PM > To: Penny, Zheng <penny.zh...@amd.com> > Cc: Stabellini, Stefano <stefano.stabell...@amd.com>; Huang, Ray > <ray.hu...@amd.com>; Ragiadakou, Xenia <xenia.ragiada...@amd.com>; > Andryuk, Jason <jason.andr...@amd.com>; Andrew Cooper > <andrew.coop...@citrix.com>; Roger Pau Monné <roger....@citrix.com>; Julien > Grall <jul...@xen.org>; Stefano Stabellini <sstabell...@kernel.org>; Anthony > PERARD <anthony.per...@vates.tech>; xen-devel@lists.xenproject.org > Subject: Re: [PATCH v1 00/11] amd-pstate CPU Performance Scaling Driver > > 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. So sorry.... Forgot we're in feature frozen window > This is intended for 4.21 then, I expect? Or else have you talked to the > release > manager? Yes, it is for 4.21 > > Jan Many thanks, Penny,
