gr-fosphor CL_INVALID_VALUE in clEnqueueFillBuffer call

Sylvain Munaut 246tnt at gmail.com
Tue Feb 7 09:01:27 UTC 2017


Hi,

> Based on your comment about how your setup doesn't support GL/CL sharing, I
> tried defining FLG_FOSPHOR_USE_CLGL_SHARING as 0 in private.h. Not sharing
> GL objects fixes the pixelated spectrum issue! No more
> cl_clear_queue_clear_buffers errors either, because the code never goes down
> that path anymore.

Ok, good to know.

I need to come up with a good way to pass "options" to fosphor to be
able to configure theses things at runtime.


> It seems to me there is a bug in the way the histogram buffer or texture is
> allocated when it is allocated through the GL code path. I'm not sure if
> this is quirk of my setup/GPU/driver, or if this is a general bug; I do have
> an older NVIDIA GPU and another machine on which I can try to reproduce what
> I'm seeing.

I can't get CL/GL sharing to work at all on my optimus laptop so
unfortunately I can't even test that code path anymore.
I really need to build myself a desktop machine ....


> Final question, what are the main downsides to NOT using CL/GL sharing? Is
> there some extra copy/performance overhead?

Yes. Basically the result of the CL computation is downloaded to CPU
memory, then re-uploaded as a texture.
Not only does that impose extra data copy but also more
synchronization points between CPU and GPU.

Cheers,

    Sylvain


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