Power Management under Nouveau

Power Management under Nouveau

[Paulo Matos]

Hello,

I would like some clarity from the developers on the state of power
management for nouveau. I have recently acquired a Dell XPS 15 (2017)
9560 with:
00:02.0 VGA compatible controller [0300]: Intel Corporation Device
[8086:591b] (rev 04)
01:00.0 3D controller [0302]: NVIDIA Corporation Device [10de:1c8d] (rev a1)

There seems to be contradictory information online with Arch Wiki
mentioning:
"Note that the open source Nvidia driver Nouveau currently does not
support power management on Pascal GPUs such as the GTX 1050, so
performance is very poor with this driver."
https://wiki.archlinux.org/index.php/Dell_XPS_15_9560

and Fedora wiki saying:
"In fact, you can no longer use the bumblebee software with nouveau any
longer even if you want to. See issue 773 for further information about
this subject. You MUST USE PRIME. The nouveau driver already handles
power saving nowadays so bumblebee would just be superfluous… "
https://fedoraproject.org/wiki/Bumblebee

However when one looks at the nouveau power support matrix:
https://nouveau.freedesktop.org/wiki/FeatureMatrix/

there's no DONE stamp on the Power management row. Is this up-to-date?

Kind regards,

-- 
Paulo Matos
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Re: Power Management under Nouveau

[Pierre Moreau]

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Hello Paulo,

Power management is made of different things:

* reclocking the memory and the engines: this is supported on some Tesla cards
  (>G92), all Kepler ones and on the first generation of Maxwell (GM10x). In
  that regard, the Arch Linux wiki is right, as Pascal cards do not support
  reclocking.

* power- and clock-gating: there’s some ongoing work for it, but none of the
  cards have upstream support for it.

* automatically suspending the card when it is not used (only for Optimus
  setups): this should work for most laptops (except for MacBooks). This is
  what the Fedora wiki is referring to.

There is also adjusting the voltage, changing the fan speed, and probably a few
others.

> there's no DONE stamp on the Power management row. Is this up-to-date?

I think so, as power- and clock gating are not supported yet, power management
support is not done yet. But the [power management feature matrix][1] seems to
be a bit out-of-date.

Cheers,
Pierre

[1]: https://nouveau.freedesktop.org/wiki/PowerManagement/

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