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OpenCL

Skysnake
Adept II

Re: Radeon 7970 questions

Thanks, for your hint.

Not very much, but better then nothing.

Is there something else? It is really little information about GCN.

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jeff_golds
Staff
Staff

Re: Radeon 7970 questions

Do you have specific questions?  The documentation will take a while to be updated.

Jeff

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alxmus
Journeyman III

Re: Radeon 7970 questions

Micah,

finally I've got the cat 12.1 for linux with support of 7970. But it looks like there is no more global buffer (aka g[ ]) access in IL  kernels for 7970. Is it true? Why?

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hazeman
Adept II

Re: Radeon 7970 questions

I don't know if new cards dont have g[], but as a workaround you can now attach 2d image to the uav ( raw or struct - i've noticed it working since driver 11.12  ) - you just need to add CAL_RESALLOC_GLOBAL_BUFFER flag ( the same as with g[] ).

I know it's not the same as having g[] ( compatibility with older cards, computing pixel shader kernels, ... ).

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MicahVillmow
Staff
Staff

Re: Radeon 7970 questions

g[] buffer has been deprecated for a few years now. Please use UAV's instead, which are more flexible than g[] buffer(32bit vs 128 bit alignment, 8bit vs 32 bit read/writes). While g[] worked on evergreen and NI hardware, it was suboptimal in many cases and the hardware does not exist for it to work on SI.

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Skysnake
Adept II

Re: Radeon 7970 questions

Yeah, i have some questions.

What is with the GDS buffer? What kind of job have it, and how can i use it?

Also is the SP:DP Ratio now 1:2 or 1:4 for the HD7k Series and much more important, it is limited, or unlimited. So will be the SP:DP different for FirePro and Radeon? For Example Radeon 1:4 FirePro 1:2

One more very important part is the x86 adress space. How can i use it with the GCN architecture?

On the FDS you have sayed that we will have this a unified adress space.

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nou
Exemplar

Re: Radeon 7970 questions

SP:DP ratio is 1:4 for 79xx cards and 1:16 for 77xx and 78xx cards.

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Skysnake
Adept II

Re: Radeon 7970 questions

Hardware or Driver limitation?

I already know that the HD7970 have only 1:4, but there is no clear answer, if this is the hardware limitation or a "driver" limitation like for the GeForce GTX580 where you have 1:8 and ond the same chip, but on a Tesla you have 1:2.

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Marix
Adept II

Re: Radeon 7970 questions

As i understood the presentation on GCN at last years Fusion this is a chip design time decision. This would also match with AMDs past policy of building different chips for different use-cases which was always reflected in the actually different code names (opposed to NVIDIAs single code name per generation).

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