linux-kernel - Re: [PATCH v2] PM / EM: Expose the Energy Model in debugfs

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Message-ID: <3845915.x0TneKyrcv@aspire.rjw.lan>
Date:   Thu, 24 Jan 2019 11:45:56 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Quentin Perret <quentin.perret@....com>
Cc:     Greg KH <gregkh@...uxfoundation.org>, rafael@...nel.org,
        peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        dietmar.eggemann@....com
Subject: Re: [PATCH v2] PM / EM: Expose the Energy Model in debugfs

On Wednesday, January 23, 2019 10:28:36 AM CET Quentin Perret wrote:
> On Tuesday 22 Jan 2019 at 19:41:36 (+0100), Greg KH wrote:
> > On Tue, Jan 22, 2019 at 04:42:47PM +0000, Quentin Perret wrote:
> > > The recently introduced Energy Model (EM) framework manages power cost
> > > tables of CPUs. These tables are currently only visible from kernel
> > > space. However, in order to debug the behaviour of subsystems that use
> > > the EM (EAS for example), it is often required to know what the power
> > > costs are from userspace.
> > > 
> > > For this reason, introduce under /sys/kernel/debug/energy_model a set of
> > > directories representing the performance domains of the system. Each
> > > performance domain contains a set of sub-directories representing the
> > > different capacity states (cs) and their attributes, as well as a file
> > > exposing the related CPUs.
> > > 
> > > The resulting hierarchy is as follows on Arm juno r0 for example:
> > > 
> > >     /sys/kernel/debug/energy_model
> > >     ├── pd0
> > >     │   ├── cpus
> > >     │   ├── cs:450000
> > >     │   │   ├── cost
> > >     │   │   ├── frequency
> > >     │   │   └── power
> > >     │   ├── cs:575000
> > >     │   │   ├── cost
> > >     │   │   ├── frequency
> > >     │   │   └── power
> > >     │   ├── cs:700000
> > >     │   │   ├── cost
> > >     │   │   ├── frequency
> > >     │   │   └── power
> > >     │   ├── cs:775000
> > >     │   │   ├── cost
> > >     │   │   ├── frequency
> > >     │   │   └── power
> > >     │   └── cs:850000
> > >     │       ├── cost
> > >     │       ├── frequency
> > >     │       └── power
> > >     └── pd1
> > >         ├── cpus
> > >         ├── cs:1100000
> > >         │   ├── cost
> > >         │   ├── frequency
> > >         │   └── power
> > >         ├── cs:450000
> > >         │   ├── cost
> > >         │   ├── frequency
> > >         │   └── power
> > >         ├── cs:625000
> > >         │   ├── cost
> > >         │   ├── frequency
> > >         │   └── power
> > >         ├── cs:800000
> > >         │   ├── cost
> > >         │   ├── frequency
> > >         │   └── power
> > >         └── cs:950000
> > >             ├── cost
> > >             ├── frequency
> > >             └── power
> > > 
> > > Signed-off-by: Quentin Perret <quentin.perret@....com>
> > > 
> > > ---
> > > 
> > > V2: removed check on return value of debugfs_create_* (Greg KH)
> > > ---
> > >  kernel/power/energy_model.c | 57 +++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 57 insertions(+)
> > 
> > Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

Applied, thanks!