Re: [PATCH 0/5] PowerManagement Toggle for PowerTOP

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Apr 13, 2016 at 12:59:18PM +0000, Zanoni, Paulo R wrote:
> Em Ter, 2016-04-12 às 12:18 -0700, Alexandra Yates escreveu:
> > This project is explained in detail on the HAS
> > https://docs.google.com/a/intel.com/document/d/1E-en_xqfHgCnhD1Tes3f0
> > 8UYrOc-etv2W-pU0ZErKdE/edit?usp=sharing  
> > 
> > Summary: 
> > Permits the user to identify and toggle values for PSR, FBC, RC6,
> > DRRS, and IPS
> > under /sys/class/drm/card0/power/.  By enabling these features I'm
> > looking to
> > empower our customers, such as, power team, chrome OS, and platform
> > integration teams
> > to debug graphics power management features. 
> > 
> > From the current patchset PSR, FBC, RC6, and, DRRS are complete and
> > past BAT, modset,
> > and suspend/resume tests.  For IPS I'm looking for feedback since IPS
> > seems to change
> > during runtime dynamically.  Additionally, as a future project IPS
> > would be better 
> > served if it is implemented by using the atomic check, pre-commit,
> > commit, post-commit,
> > a good example of this is the PSR enable/disable implementation.
> > 
> > For this project to be completed needs to have in place the following
> > components:
> > (Need to be developed)
> > * IPS toggle interface flesh-out
> > * Tests added to intel-gpu-tools repo
> > * Documentation for all sysfs added interfaces
> > * PowerTOP component named: GFX-TOP. With the following requirements:
> > 	* It would be available only to developers
> > 	* It would allow the developers to toggle the interfaces from
> > 	  the PowerTOP user interface.  
> > 	* It would show the Power Consumption impact of toggling on and
> > off
> > 	  these settings.      
> >      
> 
> A small suggestion:
> 
> In the past, I've seen people testing i915.ko power saving features
> just by "toggling" the features through the i915 module parameters
> without doing anything else. In most of these cases, the machine was
> not properly configured for power savings, so the conclusion was often
> that the feature didn't save any power. While this was true (toggling
> the feature didn't save any power), these people would have reached
> different conclusions if they had, for example, changed their disk
> power management policies. Do we have any sort of plan to try to
> educate the powertop/gfxtop users regarding these things?
> 
> Maybe the powertop/gfxtop interface could expose some very-easy-to-
> reach text explaining these things.

I think trying to extract/reuse those from the igt testcases might be
really useful. I.e. add docs that explain
a) what igt must past of a feature to be considered working
b) add some functions to igt testcases for manually enabling/disabling a
given rpm feature. The tests already know how to do that, and most have
nice explanations about what all should be changed on top to make things
work.
-Daniel

> 
> 
> > Your review of this patchset is intended to contribute to its full
> > maturity so that when we reach the PowerTOP development all pieces
> > would
> > be ready for commit.  
> > 
> > Thank you in advance,
> > 
> > Alexandra Yates (5):
> >   drm/i915: Add sys PSR toggle interface
> >   drm/i915: Add sys FBC toggle interface
> >   drm/i915: Add sys RC6 toggle interface
> >   drm/i915: Add sys drrs toggle interface
> >   drm-i915: Add sys IPS toggle interface
> > 
> >  drivers/gpu/drm/i915/i915_debugfs.c  |   5 +-
> >  drivers/gpu/drm/i915/i915_drv.c      |   5 +-
> >  drivers/gpu/drm/i915/i915_drv.h      |  12 ++
> >  drivers/gpu/drm/i915/i915_sysfs.c    | 362
> > ++++++++++++++++++++++++++++++++++-
> >  drivers/gpu/drm/i915/intel_color.c   |  12 +-
> >  drivers/gpu/drm/i915/intel_ddi.c     |  15 +-
> >  drivers/gpu/drm/i915/intel_display.c |  55 ++++--
> >  drivers/gpu/drm/i915/intel_dp.c      |  48 +++--
> >  drivers/gpu/drm/i915/intel_drv.h     |  21 +-
> >  drivers/gpu/drm/i915/intel_fbc.c     |  29 ++-
> >  drivers/gpu/drm/i915/intel_pm.c      |  53 ++++-
> >  drivers/gpu/drm/i915/intel_psr.c     |  36 +++-
> >  12 files changed, 588 insertions(+), 65 deletions(-)
> > 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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