Re: [PATCH] powercap/rapl: handle domain energy unit

From: Rafael J. Wysocki
Date: Thu Mar 12 2015 - 18:01:19 EST


On Thursday, March 12, 2015 01:17:39 PM Jacob Pan wrote:
> On Wed, 11 Mar 2015 23:01:30 +0100
> "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> wrote:
>
> > On Wednesday, March 11, 2015 05:55:09 AM Jacob Pan wrote:
> > > The current driver assumes all RAPL domains within a CPU package
> > > have the same energy unit. This is no longer true for HSW server
> > > CPUs since DRAM domain has is own fixed energy unit which can be
> > > different than the package energy unit enumerated by package
> > > power MSR. In fact, the default HSW EP package power unit is 61uJ
> > > whereas DRAM domain unit is 15.3uJ. The result is that DRAM power
> > > consumption is counted 4x more than real power reported by energy
> > > counters.
> > >
> > > This patch adds domain specific energy unit per cpu type, it allows
> > > domain energy unit to override package energy unit if non zero.
> > >
> > > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> >
> > Should I regard this as a fix for 4.0? If so, should it also go to
> > "stable" (and which "stable" series should it go to in that case)?
> >
> yes, it is a bug fix. I think this should be applied to all stable
> kernels since RAPL driver was merged. So 3.10.71 and later.

OK

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