[Public] > -----Original Message----- > From: Jan Beulich <jbeul...@suse.com> > Sent: Tuesday, May 20, 2025 5:18 PM > To: Penny, Zheng <penny.zh...@amd.com> > Cc: Huang, Ray <ray.hu...@amd.com>; Anthony PERARD > <anthony.per...@vates.tech>; xen-devel@lists.xenproject.org > Subject: Re: [PATCH v4 12/15] tools/xenpm: Print CPPC parameters for amd-cppc > driver > > On 20.05.2025 10:22, Penny, Zheng wrote: > >> -----Original Message----- > >> From: Jan Beulich <jbeul...@suse.com> > >> Sent: Tuesday, May 13, 2025 4:03 PM > >> > >> On 09.05.2025 08:36, Penny, Zheng wrote: > >>>> -----Original Message----- > >>>> From: Jan Beulich <jbeul...@suse.com> > >>>> Sent: Wednesday, April 30, 2025 9:55 PM > >>>> > >>>> On 14.04.2025 09:40, Penny Zheng wrote: > >>>>> HWP, amd-cppc, amd-cppc-epp are all the implementation of ACPI > >>>>> CPPC (Collaborative Processor Performace Control), so we introduce > >>>>> cppc_mode flag to print CPPC-related para. > >>>>> > >>>>> And HWP and amd-cppc-epp are both governor-less driver, so we > >>>>> introduce hw_auto flag to bypass governor-related print. > >>>> > >>>> But in the EPP driver you use the information which governor is active. > >>> > >>> We want to have a one-one mapping between governor and epp value, > >>> such as, If users choose performance governor, no matter via "xenpm" > >>> or cmdline, users want maximum performance, We set epp with 0 to > >>> meet the > >> expectation. > >>> And if users choose powersave governor, users want the least power > >>> consumption, then we shall set epp with 255 to meet the expectation. > >> > >> That's all fine, but completely misses the point of my question: If > >> the governor is relevant, why would you bypass respective printing? > >> > > > > The only useful info in governor for epp mode, IMO, is its name. > > I deduce which performance policy user wants to apply through which governor > they choose. > > If user chooses performance governor, they want maximum performance. > > If user chooses powersave governor, they want the least power > > consumption I could only provide appropriate epp value in above two > > scenarios. > > ondemand and userspace are forbidden choices, and if users specify > > such options in cmdline, I shall give warning message to say that > > amd-cppc in active mode is governor-less, and users could set epp values on > runtime to specify bias towards performance or efficiency. > > > > If above is messy, I could also totally forbid governor thing for active > > mode... > wdyt? > > Then how would one pick between performance and powersave?
In hwp, we defined " #define CPPC_ENERGY_PERF_BALANCE 0x80 " to provide the balanced value. Users could run "xenpm set-cpufreq-cppc balance" to achieve on runtime Any other specific epp value, users shall run "xenpm set-cpufreq-cppc energy-perf:N" to achieve We didn't provide any options in cmdline, so I tried to re-use the governor to achieve a few. hmmm, now it seems it brings confusion.... > > Jan
