Hi,
In data venerd? 16 ottobre 2020 16:43:09 CEST, Mark Pearson ha scritto:
> <Note - switched my email address to my more open source non-outlook
> based address>
>
> On 2020-10-16 10:32 a.m., Mark Pearson wrote:
> > ------------------------------------------------------------------------
> > *From:* Elia Devito <[email protected]>
> > *Sent:* October 16, 2020 10:26
> > *To:* Rafael J. Wysocki <[email protected]>; Hans de Goede
> > <[email protected]>
> > *Cc:* Daniel Lezcano <[email protected]>; Srinivas Pandruvada
> > <[email protected]>; Lukasz Luba
> > <[email protected]>; Linux Kernel Mailing List
> > <[email protected]>; Linux PM <[email protected]>;
> > Zhang, Rui <[email protected]>; Bastien Nocera <[email protected]>;
> > Mark Pearson <[email protected]>; Limonciello, Mario
> > <[email protected]>; Darren Hart <[email protected]>; Andy
> > Shevchenko <[email protected]>; Mark Gross <[email protected]>;
> > Benjamin Berg <[email protected]>; [email protected]
> > <[email protected]>; [email protected]
> > <[email protected]>
> > *Subject:* [External] Re: [RFC] Documentation: Add documentation for new
> > performance_profile sysfs class (Also Re: [PATCH 0/4] powercap/dtpm: Add
> > the DTPM framework)
> > Hi,
> >
> > In data venerd? 16 ottobre 2020 13:10:54 CEST, Hans de Goede ha scritto:
> >> <note folding the 2 threads we are having on this into one, adding every
> >> one from both threads to the Cc>
> >>
> >> Hi,
> >>
> >> On 10/14/20 5:42 PM, Rafael J. Wysocki wrote:
> >> > On Wed, Oct 14, 2020 at 4:06 PM Hans de Goede <[email protected]>
wrote:
> >> >> On 10/14/20 3:33 PM, Rafael J. Wysocki wrote:
> >> <snip>
> >>
> >> >>> First, a common place to register a DPTF system profile seems to be
> >> >>> needed and, as I said above, I wouldn't expect more than one such
> >> >>> thing to be present in the system at any given time, so it may be
> >> >>> registered along with the list of supported profiles and user space
> >> >>> will have to understand what they mean.
> >> >>
> >> >> Mostly Ack, I would still like to have an enum for DPTF system
> >> >> profiles in the kernel and have a single piece of code map that
> >> >> enum to profile names. This enum can then be extended as
> >> >> necessary, but I want to avoid having one driver use
> >> >> "Performance" and the other "performance" or one using
> >> >> "performance-balanced" and the other "balanced-performance", etc.
> >> >>
> >> >> With the goal being that new drivers use existing values from
> >> >> the enum as much as possible, but we extend it where necessary.
> >> >
> >> > IOW, just a table of known profile names with specific indices assigned
> >> > to
> >> > them.
> >>
> >> Yes.
> >>
> >> > This sounds reasonable.
> >> >
> >> >>> Second, irrespective of the above, it may be useful to have a
> >> >>> consistent way to pass performance-vs-power preference information
> >> >>> from user space to different parts of the kernel so as to allow them
> >> >>> to adjust their operation and this could be done with a system-wide
> >> >>> power profile attribute IMO.
> >> >>
> >> >> I agree, which is why I tried to tackle both things in one go,
> >> >> but as you said doing both in 1 API is probably not the best idea.
> >> >> So I believe we should park this second issue for now and revisit it
> >> >> when we find a need for it.
> >> >
> >> > Agreed.
> >> >
> >> >> Do you have any specific userspace API in mind for the
> >> >> DPTF system profile selection?
> >> >
> >> > Not really.
> >>
> >> So before /sys/power/profile was mentioned, but that seems more like
> >> a thing which should have a set of fixed possible values, iow that is
> >> out of scope for this discussion.
> >>
> >> Since we all seem to agree that this is something which we need
> >> specifically for DPTF profiles maybe just add:
> >>
> >> /sys/power/dptf_current_profile (rw)
> >> /sys/power/dptf_available_profiles (ro)
> >>
> >> (which will only be visible if a dptf-profile handler
> >>
> >> has been registered) ?
> >>
> >> Or more generic and thus better (in case other platforms
> >> later need something similar) I think, mirror the:
> >>
> >> /sys/bus/cpu/devices/cpu#/cpufreq/energy_performance_* bits
> >> for a system-wide energy-performance setting, so we get:
> >>
> >> /sys/power/energy_performance_preference
> >> /sys/power/energy_performance_available_preferences
> >>
> >> (again only visible when applicable) ?
> >>
> >> I personally like the second option best.
> >>
> >> Regards,
> >>
> >> Hans
> >
> > between the two, the second seems to me more appropriate.
> > Considering that the various profiles interact with thermal behaviors
> > what do
> > you think of something like:
> >
> > /sys/power/thermal_profile_available_profiles
> > /sys/power/thermal_profile_profile
> >
> > Regards,
> > Elia
>
> I'm good with either but I do find 'profile_profile' slightly awkward to
> say out loud (even though it's logically correct :))
>
> How about just:
> /sys/power/platform_profile
> /sys/power/platform_profile_available
>
> As it covers the platform as a whole - fans, temperature, power, and
> anything else that ends up getting thrown in?
>
> Mark
Completely agree, I made a typo xD
Elia