linux-kernel - Re: [PATCH] platform/x86/intel-uncore-freq: Do not present separate package-die domain

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Message-ID: <3982985e-d8c1-7307-7187-aae438d9b75e@linux.intel.com>
Date: Tue, 13 Aug 2024 10:51:43 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: srinivas pandruvada <srinivas.pandruvada@...ux.intel.com>
cc: Hans de Goede <hdegoede@...hat.com>, 
    Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
    platform-driver-x86@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] platform/x86/intel-uncore-freq: Do not present separate
 package-die domain

On Mon, 12 Aug 2024, srinivas pandruvada wrote:
> On Mon, 2024-08-12 at 14:16 +0300, Ilpo Järvinen wrote:
> > On Wed, 31 Jul 2024, Srinivas Pandruvada wrote:
> > 
> > > The scope of uncore control is per power domain in a package and
> > > die.
> > > A package-die can have multiple power domains on some processors.
> > > In this
> > > case package-die domain (root domain) aggregates all information
> > > from
> > > power domains in it.
> > > 
> > > On some processors, CPUID enumerates the die number same as power
> > > domain
> > > ID. In this case there is one to one relationship between package-
> > > die and
> > > power domain ID. There is no use of aggregating information from
> > > all
> > > power domain IDs as the information will be duplicate and
> > > confusing. In
> > > this case do not create separate package-die domain.
> > 
> > Hi Srinivas,
> > 
> > I got confused by this changelog because its order is quite
> > illogical.
> > 
> > First paragraph talks about case A. When you say "all information" 
> > is "aggregated", I immediately make the assumption that the
> > aggregated 
> > information is what is wanted because, well, you normally want "all 
> > information" and nothing else is being told here.
> > 
> > Second paragraph starts to talk about case B and then suddenly
> > switches to 
> > talk what should have been done in case A (that aggregated
> > information is 
> > useless/confusing).
> > 
> Is this any better:
> 
> "
> The scope of uncore control is per power domain in a package and die
> with TPMI.
> 
> There are two types of processor configurations possible:
> 1. A compute die is not enumerated in CPUID. In this case there is only
> one die in a package. In this case there will be multiple power domains
> in a single die.
> 2. A power domain in a package is enumerated as a compute die in CPUID.
> So there is one to one relationship between a die and power domain.

So there are multiple dies in a package and one to one relationship 
between a die and power domain.

?

> 
> To allow die level controls, the current implementation creates a root
> domain and aggregates all information from power domains in it. This
> is well suited for configuration 1 above.
> 
> But when newer processors use configuration 2 above, this will present
> redundant information, So no use of aggregating. In this case do not
> create separate root domain.
> "

Yes, it is now clearer. A minor suggestion above to better map with the 
code (explicitly stating the condition that matches to the check done
by the code).

-- 
 i.