power capping values on dbus

power capping values on dbus

[Zbyszek]

Hi everyone!

I would like to expose on dbus values like min and max power capping.
These values could be read from files provided by hwmon like:
   power[1-*]_cap_max,
   power[1-*]_cap_min
which are describe here:
https://www.kernel.org/doc/Documentation/hwmon/sysfs-interface

I have noticed that this interface:
https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/xyz/openbmc_project/Sensor/Value.interface.yaml
is already exposing something like MinValue and MaxValue,
but current implementation in dbus-sensors always sets these
attributes to some const values.
My understanding of the power capping values is that they could be used as these
MinValue and MaxValue if hwmon provides them otherwise some default
should be used as it is now.


My questions:
1. Should I create a new interface for the capping readings?
2. Or should I extend the existing Value.interface.yaml with new
attributes like MinCapValue, MaxCapValue?
3  Or the correct approach would be to read the cap values if provided
and expose them under already existing MinValue, MaxValue?


Regards,
Zbigniew.

Re: power capping values on dbus

[Adrian Ambrożewicz]

I don't think it's clear from your message what you are trying to achieve:
a) ability to expose power capping information as dbus-sensor just as 
read-only information
b) ability to set the cap through D-Bus interface

I suspect it's the former (just exposing data). If that's so I don't 
think you need any new interface at all. You could just add a 'Cap' 
sensor, eg Cpu0PowerCap and all the values fits nicely.

For latter, there already exist interface for configuring power capping 
(https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/xyz/openbmc_project/Control/Power/Cap.interface.yaml), 
however it doesn't specify properties for Min and Max values.

Regards,
Adrian

W dniu 5/26/2020 o 14:46, Zbyszek pisze:
> Hi everyone!
> 
> I would like to expose on dbus values like min and max power capping.
> These values could be read from files provided by hwmon like:
>     power[1-*]_cap_max,
>     power[1-*]_cap_min
> which are describe here:
> https://www.kernel.org/doc/Documentation/hwmon/sysfs-interface
> 
> I have noticed that this interface:
> https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/xyz/openbmc_project/Sensor/Value.interface.yaml
> is already exposing something like MinValue and MaxValue,
> but current implementation in dbus-sensors always sets these
> attributes to some const values.
> My understanding of the power capping values is that they could be used as these
> MinValue and MaxValue if hwmon provides them otherwise some default
> should be used as it is now.
> 
> 
> My questions:
> 1. Should I create a new interface for the capping readings?
> 2. Or should I extend the existing Value.interface.yaml with new
> attributes like MinCapValue, MaxCapValue?
> 3  Or the correct approach would be to read the cap values if provided
> and expose them under already existing MinValue, MaxValue?
> 
> 
> Regards,
> Zbigniew.
> 

Re: power capping values on dbus

[Zbyszek]

wt., 26 maj 2020 o 15:01 Adrian Ambrożewicz
<adrian.ambrozewicz@linux.intel.com> napisał(a):
>
> I don't think it's clear from your message what you are trying to achieve:
> a) ability to expose power capping information as dbus-sensor just as
> read-only information
> b) ability to set the cap through D-Bus interface
>
> I suspect it's the former (just exposing data). If that's so I don't
> think you need any new interface at all. You could just add a 'Cap'
> sensor, eg Cpu0PowerCap and all the values fits nicely.

Yes, that is exactly what I want to achieve :)
Your solution sound very good, it will allow me to expose power
capping information
without any modifications to dbus-interfaces at all.
I will soon push some implementation to review under dbus-sensor.
Thanks.

>
> For latter, there already exist interface for configuring power capping
> (https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/xyz/openbmc_project/Control/Power/Cap.interface.yaml),
> however it doesn't specify properties for Min and Max values.
>
> Regards,
> Adrian
>
> W dniu 5/26/2020 o 14:46, Zbyszek pisze:
> > Hi everyone!
> >
> > I would like to expose on dbus values like min and max power capping.
> > These values could be read from files provided by hwmon like:
> >     power[1-*]_cap_max,
> >     power[1-*]_cap_min
> > which are describe here:
> > https://www.kernel.org/doc/Documentation/hwmon/sysfs-interface
> >
> > I have noticed that this interface:
> > https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/xyz/openbmc_project/Sensor/Value.interface.yaml
> > is already exposing something like MinValue and MaxValue,
> > but current implementation in dbus-sensors always sets these
> > attributes to some const values.
> > My understanding of the power capping values is that they could be used as these
> > MinValue and MaxValue if hwmon provides them otherwise some default
> > should be used as it is now.
> >
> >
> > My questions:
> > 1. Should I create a new interface for the capping readings?
> > 2. Or should I extend the existing Value.interface.yaml with new
> > attributes like MinCapValue, MaxCapValue?
> > 3  Or the correct approach would be to read the cap values if provided
> > and expose them under already existing MinValue, MaxValue?
> >
> >
> > Regards,
> > Zbigniew.
> >