Slow performance using eGPU with lid closed

[Michel Dänzer]

On 2019-05-05 3:06 a.m., Qu Wenruo wrote:
> On 2019/4/29 下午10:11, Michel Dänzer wrote:
>> On 2019-04-29 3:04 p.m., Qu Wenruo wrote:
>>
>>> Is it possible to disable Intel one completely at X start time?
>>>
>>> Just regular xorg.conf.d with amdgpu only device section?
>>
>> Sure, but then you won't be able to power down the AMD GPU while Xorg is
>> running (or at least while it's active).
> 
> Considering current kernel eGPU support, hot unplug is impossible as it
> will panic the amdgpu module, so it's not a big deal.

FWIW, another possible gotcha is that DRI_PRIME=1 will result in apps
using the Intel GPU for rendering then.


> While the bigger problem is the config. As normally Xorg auto detect is
> good enough and user needs no extra config.
> 
> But with such eGPU setup, if only have 10-amdgpu.conf and 20-intel.conf,

Unless you've modified it, 10-amdgpu.conf just instructs Xorg to use the
xf86-video-amdgpu driver for any devices controlled by the amdgpu kernel
driver by default; it doesn't affect which GPU Xorg uses as primary.

Where is 20-intel.conf from, and what does it contain?

The xorg.conf.d mechanism is for shipping configuration snippets in
packages. For user configuration, /etc/X11/xorg.conf should be used.


> without screen specification, X will not start due to failure to find
> screen.
> 
> I'm wondering what's the correct way to specify all the needed config.
> to make X work with, and without eGPU.

This should be all you need to choose the primary GPU:

Section "Device"
        Identifier "AnythingYouLike"
	BusID	"PCI:<as printed in Xorg log file, e.g. 34 at 0:0:0>"
EndSection


If you don't want Xorg to use the non-primary GPU at all (it can still
be used via DRI3), add

Section "ServerFlags"
       Option	"AutoAddGPU" "off"
EndSection


-- 
Earthling Michel Dänzer               |              https://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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