OpenCL/OpenGL contention on a device (was Re: x11/nvidia-driver-340 and OpenCL)

[Arto Pekkanen]

I was not talking about working sets that require all of the VRAM on the
GPU. I was thinking of a situation where the computing jobs use only a
portion of memory, leaving plenty available for graphics operations. In
that case me and my friends haven't seen any stuttering on most mid-tier
nVidia and AMD cards.

I might try running a VRAM hogging computing job on my Windows box, but
I assume the driver is smart enough to prioritize graphics resources
over computing resources in VRAM and limit the number of fetches from
RAM on computing kernels to prevent bus saturation etc.

On 31.8.2017 11:43, Scott Bennett wrote:
> Arto Pekkanen <isoa at kapsi.fi> wrote:
> 
>> If the GPU driver is implemented properly there will be no stutter or
>> other problems even when running OpenCL jobs.
> 
>      Really!  So an OpenCL work item that needs, say, nearly all the available
> memory on a graphics device and a 3D shader that has similar memory
> requirements will not interfere with each other?  That seems rather magical
> somehow, even if the OpenGL stuff always has a higher priority inside the GPU
> than the OpenCL stuff.
>>
>> In Windows there is no problem running OpenCL jobs on the same device
>> that operates your display. Like running a crypto currency miner while
>> browsing the web. Playing games won't work well, but basic stuff you can do.
>>
>      Is that partly because the memory requirements of the "basic stuff" are
> typically tiny when compared to the capacity of today's graphics devices?
> 
>> TL;DR when the FreeBSD GPU driver and all the userland bits are up to
>> date, I'd expect there to be no issues with stuttering.
>>
>      Do you know the driver well enough to explain to me how the scheduling
> inside a graphics device works?  I've never seen a description of the
> algorithm(s) anywhere.
> 
> 
>                                   Scott Bennett, Comm. ASMELG, CFIAG
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> 

-- 
Arto Pekkanen

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