Re: driver model, duplicate names question

[Srinivas Pandruvada]

On 07/16/2013 12:04 PM, Greg KH wrote:
> A: No.
> Q: Should I include quotations after my reply?
>
> http://daringfireball.net/2007/07/on_top
Glad to learn something new today.
> On Tue, Jul 16, 2013 at 11:54:31AM -0700, Srinivas Pandruvada wrote:
> > Hi,
> >
> > I am assigned to do add a powercap class. There are several
> > technologies, which will allow to add a power budget to an individual
> > device. For example, you can set a power budget to a individual
> > physical cpu package, each core and uncore devices, GPUs, DRAM etc.
> "classes" all reference a "device" in the system, I don't see that in
> your tree below, where does that come in?  How do I, as someone who
> created a device in the system know to create a your new powercap class
> for it?
>
> In other words, are you _sure_ you want a class here and not something
> else (i.e. a bus?)
>
> > +The Power Capping framework organizes power capping devices under a tree structure.
> > +At the root level, each device is under some "controller", which is the enabler
> > +of technology. For example this can be "RAPL".
> > +Under each controllers, there are multiple power zones, which can be independently
> > +monitored and controlled.
> > +Each power zone can be organized as a tree with parent, children and siblings.
> > +Each power zone defines attributes to enable power monitoring and constraints.
> Ah, this sounds like you want to be a bus, as you have a controller, and
> then devices attached to it.
>
> > +Example Sys-FS Interface
> > +
> > +/sys/class/power_cap/intel-rapl
> > +âââ package-0
> > +â   âââ constraint-0
> > +â   â   âââ name
> > +â   â   âââ power_limit_uw
> > +â   â   âââ time_window_us
> > +â   âââ constraint-1
> > +â   â   âââ name
> > +â   â   âââ power_limit_uw
> > +â   â   âââ time_window_us
> > +â   âââ core
> > +â   â   âââ constraint-0
> > +â   â   â   âââ name
> > +â   â   â   âââ power_limit_uw
> > +â   â   â   âââ time_window_us
> > +â   â   âââ energy_uj
> > +â   â   âââ max_energy_range_uj
> > +â   âââ dram
> > +â   â   âââ constraint-0
> > +â   â   â   âââ name
> > +â   â   â   âââ power_limit_uw
> > +â   â   â   âââ time_window_us
> > +â   â   âââ energy_uj
> > +â   â   âââ max_energy_range_uj
> > +â   âââ energy_uj
> > +â   âââ max_energy_range_uj
> > +â   âââ max_power_range_uw
> > +âââ package-1
> > +â   âââ constraint-0
> > +â   â   âââ name
> > +â   â   âââ power_limit_uw
> > +â   â   âââ time_window_us
> > +â   âââ constraint-1
> > +â   â   âââ name
> > +â   â   âââ power_limit_uw
> > +â   â   âââ time_window_us
> > +â   âââ core
> > +â   â   âââ constraint-0
> > +â   â   â   âââ name
> > +â   â   â   âââ power_limit_uw
> > +â   â   â   âââ time_window_us
> > +â   â   âââ energy_uj
> > +â   â   âââ max_energy_range_uj
> > +â   âââ dram
> > +â   â   âââ constraint-0
> > +â   â   â   âââ name
> > +â   â   â   âââ power_limit_uw
> > +â   â   â   âââ time_window_us
> > +â   â   âââ energy_uj
> > +â   â   âââ max_energy_range_uj
> > +â   âââ energy_uj
> > +â   âââ max_energy_range_uj
> > +â   âââ max_power_range_uw
> > +âââ power
> > +â   âââ async
> > +â   âââ autosuspend_delay_ms
> > +â   âââ control
> > +â   âââ runtime_active_kids
> > +â   âââ runtime_active_time
> > +â   âââ runtime_enabled
> > +â   âââ runtime_status
> > +â   âââ runtime_suspended_time
> > +â   âââ runtime_usage
> > +âââ subsystem -> ../../../../class/power_cap
> > +âââ uevent
> Ick.  Rewrite this to use a bus and you should be fine, right?  Don't
> use a class, a class is only to be used if you have a device that is a
> specific "type of thing".  Like a tty device, it is a class, as lots of
> different "real" devices can have tty ports on them (usb, pci, pcmcia,
> platform, etc.)
>
> Rethink this using a bus and see if that solves your issues.  You get a
> hierarchy with that.  And you can have different "types" of devices on
> your bus, making it easy to tell the difference between a "package" and
> a "constraint".
>
> Does that help?
I will experiment your suggestion. I see this class analogous to 
"/sys/class/thermal",
, where the thermal class provides a set of consistent interface for all 
thermal devices.
> greg k-h
Thanks,
Srinivas
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/