On 08/15/2010 02:51 AM, tobias appelo wrote:
Hi there,
I was wondering what's the best way to reduce gpu power usage on a
server or desktop that is not required to run X. It appears to me that
this is still very common and I would like to save as much pwer as possible.
I did some testing on desktops / laptops with intel integrated graphics,
a desktop with an nvidia card and a desktop with an integrated ati video
card and in each case the amount of watts that the whole system used
(measured from wall) became less after initialization of X. (saved
around 5 watts).
Turning the monitor off using xrandr saved 5 watts more.
In case of the nvidia and ati card I used the proprietary driver as it
gave me better results when starting X.
Simply modprobing the graphis driver did not lower the amount of watts
used. Also, experimenting with underclockutilities such as rovclock or
nvclock did not produce the same amount of powersaving (only about 3
watts) as just starting X.
Currently I use a fluxbox setup to get the power usage as low as
possible (and xrandr automatically turns off the monitor using fluxbox
startup file), but I do not like installing all kinds of X software on
systems that do not require it. Is there another way to reduce the GPU
power usage in console mode ?
Well, you could remove the power-hungry graphics card alltogether. This
might be an option if the system has on-board graphics.
Intel's gfx chipsets will use kernel-modesetting which means that the
graphics chipset will be fully initialized at boot time and you'll get
the powersavings that way without running Xorg at all.
As for other chipset vendors, they'll need to add kernel driver support
to enable power savings features for when the adapter is not in graphics
mode, this isn't something you can do without Xorg since most of the
hardware code is actually controlled by the userspace X drivers.
Auke
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