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boxerab
Challenger

Tonga delta color compression

I have a bandwidth-hungry set of kernels. So, I am really looking forward to moving from HD 7700 to new Fiji air cooled.

Even with 512 GB/s, I want more!  Will delta color compression increase bandwidth to global memory?  My data is very

compressible - lots of redundancy.

Thanks!

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1 Solution
tzachi_cohen
Staff

Yes, DCC will better utilize bandwidth to global memory.

DCC is abstracted away from the application or the operating system. There is no DCC flag the application can specify.

In the context of OCL, DCC may only be engaged for read only images.

Tzachi

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6 Replies
tzachi_cohen
Staff

Yes, DCC will better utilize bandwidth to global memory.

DCC is abstracted away from the application or the operating system. There is no DCC flag the application can specify.

In the context of OCL, DCC may only be engaged for read only images.

Tzachi

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When you mention read only images, do you mean images created with the flag CL_MEM_READ_ONLY, or do you mean images that are passed

into a kernel as read_only​?

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Bump..... Tzachi: when you mentioned DCC is for read only images,  do you mean images created with the flag CL_MEM_READ_ONLY, or do you mean images that are passed into a kernel as read_only?  Thanks!

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boxerab
Challenger

Thanks, Tzachi! Why will DCC not apply to simple buffers in global memory? Because this is where I need the most bandwidth in my kernel. Might this be added in the future, with a flag to indicate a read only buffer?

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DCC, stands for delta COLOR compression. The only construct that keeps color data in a format which is well specified, both to the application and GPU, are image objects.

Bear in mind that this feature was invented for graphics, where the use of image objects (AKA textures) is much more prevalent.

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Thanks, makes sense. I am looking into modifying my kernel to use an image rather than a buffer, so I can make use of the glorious new

compression. By the way, it would be nice to have a blog post on how to best make use of the Fiji board with opencl.

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