Re: Cygwin/X causes NVIDIA GPU to turn on in Optimus systems

[Thiago Padilha <tpadilha84@gmail.com>]

Hi,

I also have nvidia optimus and noticed this problem but with me the
nvidia gpu only kicks in for a brief time whenever a x application is
started, so the extra enery consumed is very small. It is anoying all
the same, I appreciate any workaround for this.

On Tue, Mar 26, 2013 at 12:58 PM, Aaron A. Kelley
<aaronkelley@hotmail.com> wrote:
> For those that aren’t aware, NVIDIA Optimus is a feature that makes use of
> the Intel GPU that is included in new Intel Core i series processors (Sandy
> Bridge and up).  Basically, in a system that has both the integrated Intel
> GPU and also a discrete NVIDIA GPU, the Intel GPU is used for most desktop
> operations and the NVIDIA GPU kicks in when the graphics power is needed for
> games and other processing jobs.  This is done to save power --- if the
> NVIDIA GPU can spend most of its time powered down, your battery lasts
> longer.  The NVIDIA card can be used to run only particular applications
> individually, and its output is dumped over to the Intel GPU for display
> using some fast framebuffer magic.
>
> I usually leave Cygwin/X open on my machine because I use it to access GUI
> apps running in SSH terminals from time to time.  Today I noticed that in an
> Optimus environment, it is causing the NVIDIA GPU to kick in, which causes
> the NVIDIA GPU to stay powered on when maybe it doesn’t need to.
>
> http://stuff.aaron-kelley.net/2013/03/cygxoptimus.png
>
> I went to the NVIDIA control panel and set xwin.exe specifically to use the
> integrated GPU but it still says that xwin.exe is running on the NVIDIA GPU
> when I run it.  Cygwin/X must be doing something unusual at initialization
> that makes the NVIDIA card feel like it has to kick on.  I don’t have to
> actually launch any X windows to see this occur, it happens moments after I
> launch the Cygwin/X server.
>
> I haven’t been able to find anyone else mentioning this.  It may be because
> Optimus configurations aren’t very common.  This also means that this issue
> may be tricky to track down.  I’m not sure if it will be easy to find
> someone who knows about Cygwin/X development who also has access to an
> Optimus environment.  This might be something that has to go for NVIDIA for
> them to fix in their drivers, but it’d be nice to know a little more about
> the issue before trying to get in touch with them.
>
> I’m interested in doing anything I can do help address this but I don’t know
> where to begin, so I’m welcoming your feedback.
>
> Thanks,
>
> --
> Aaron
>
>
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