Diagnosing first vs subsequent performance

Lloyd Brown lloyd_brown at byu.edu
Thu Jan 21 07:30:32 PST 2016

Just so I know, is there an xorg.conf equivalent of the "-sharevts" cli
parameter?  I see (but haven't tested) a "DontVTSwitch" documented,
which I assume is the equivalent of "-novtswtich".  But I haven't seen
anything for "-sharevts".

It's not a huge deal either way.  Just a personal preference to have
config files vs cli params.


On 01/20/2016 04:57 PM, Lloyd Brown wrote:
> Wow, Aaron.  I should've known that you'd have the answer.  Thanks, btw,
> for answering my earlier, semi-related questions on the nvidia forum:
> https://devtalk.nvidia.com/default/topic/840157/non-root-xorg-with-nvidia-driver/
> In short, adding the sharevts and novtswitch to the command-line for the
> Xorg instances, it seems to be working, though I'll have to do some more
> tests, and lots more scheduler integration work.  For reference, here's
> a screenshot of 4 separate glxgears output, as well as nvidia-smi
> showing the GPU load and PIDs doing it:
> https://drive.google.com/file/d/0B4ng6id1VlIOT245dFFuc21jZW8/view?usp=sharing
> Thanks everybody,
> Lloyd
> On 01/20/2016 03:09 PM, Aaron Plattner wrote:
>> My guess is that each X server you start is switching to its own VT.
>> Since you're running Xorg by itself, there are initially no clients
>> connected.  When you run an application such as glxinfo that exits
>> immediately, or kill your copy of glxgears, it causes the server to
>> reset, which makes it initiate a VT switch to itself.  Only the X server
>> on the active VT is allowed to touch any of the hardware, so the other X
>> servers revoke GPU access whenever the one you touched last grabs the VT.
>> You can work around this problem somewhat by using the -sharevts and
>> -novtswitch options to make the X servers be active simultaneously, but
>> please be aware that this configuration is not officially supported so
>> you might run into strange and unexpected behavior.

Lloyd Brown
Systems Administrator
Fulton Supercomputing Lab
Brigham Young University

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