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OpenCL

jrauch
Journeyman III
Journeyman III

HD 6790 double precision?

Hi,

I have a Sapphire HD 6790 card which according to the AMD Specs does  have double precision capabilites:

http://www.amd.com/us/products/desktop/graphics/amd-radeon-hd-6000/hd-6790/Pages/amd-radeon-hd-6790-overview.aspx#3

I installed acmlgpu1.1.2, and Catlyst 11.6. When I execute "GPGPUexamples/Info.exe" I get in the gpu part:

gpu0:
    Type:                            CALtarget(17) (unknown type)
    Revision:                          20
    Maximum resource 1D width:       16384
    Maximum resource 2D width:       16384
    Maximum resource 2D height:      16384
    Local GPU RAM:                   1024 megabytes
    Uncached remote GPU memory:      1788 megabytes
    Cached remote GPU memory:         508 megabytes
    GPU device clock rate:            840 megahertz
    GPU memory clock rate:           1050 megahertz
    Wavefront size:                    64
    Number of SIMDs:                   10
    Number of shader engines:           2
    double precision:                Not supported
    local data share:                Supported
    global data share:               Supported
    global GPR:                      Supported
    compute shader:                  Supported
    memexport:                       Supported
    calResCreate pitch alignment:     256 data elements
    calResCreate address alignment:   256 bytes
    Unaligned Access Views (UAVs):     12
    3D program grid:                 Supported

 

Note the "not supported" for "double precision". Running "/gfortran/examples/performance/time_dgemm.exe" I get:

"Warning:  no suitable GPUs found for double-precision GPGPU operations."

What's going on here?

Best regards,

Jonas

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4 Replies
Meteorhead
Challenger
Challenger

HD 6790 double precision?

I suspect that is a serious copy-paste mistake. Only the high-end GPUs support DP precision. When this is the case, compute power is always listed seperately for SP and DP. HD 6790 does not support DP, even if it is listed on the website. A dire mistake indeed.

HD5850, HD5870, HD5970, HD6950, HD6970, HD6990 are the only graphics cards that support DP operations.

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jrauch
Journeyman III
Journeyman III

HD 6790 double precision?

First of all, thanks you the quick reply!

That is very sad. I chose the card because I wanted to make some numerical experiments with the GPU. Guess I'm stuck with my CPU now ;-(

Regards,

Jonas

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Meteorhead
Challenger
Challenger

HD 6790 double precision?

While it is very frustrating if one choses something in hope for a feature, which turns out is not present, using OpenCL for CPU computing might still be worthy, as AMD compiler is very adept at vectorizing code with SSE instructions.

My findings are is that it outperforms gcc about 10 times on an Intel Core-i7 when using serial code vs. OpenCL kernels.

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himanshu_gautam
Grandmaster
Grandmaster

HD 6790 double precision?

jrauch,

Sorry for the inconvenience caused to you. I will ask someone to remove the Double capability from that page.

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