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Compute Performance

Moving on from our look at gaming performance, we have our customary look at compute performance. With GCN AMD significantly overhauled their architecture in order to improve compute performance, as their long-run initiatives rely on GPU compute performance becoming far more important than it is today.

With such a move however AMD has to solve the chicken and the egg problem on their own, in this case by improving compute performance before there are really a large variety of applications ready to take advantage of it. As we’ll see AMD has certainly achieved that goal, but it raises the question of what was the tradeoff for that? We have some evidence that GCN is more efficient than VLIW5 on a per-shader basis even in games, but at the same time we can’t forget that AMD has gone from 800 SPs to 640 SPs in the move from Juniper to Cape Verde, in spite of a full node jump in fabrication technology. In the long run AMD will be better off, but I suspect we’re looking at that tradeoff today with the 7700 series.

Our first compute benchmark comes from Civilization V, which uses DirectCompute to decompress textures on the fly. Civ V includes a sub-benchmark that exclusively tests the speed of their texture decompression algorithm by repeatedly decompressing the textures required for one of the game’s leader scenes. Note that this is a DX11 DirectCompute benchmark.

Theoretically the 5770 has a 5% compute performance advantage over the 7770. In practice the 5770 doesn’t stand a chance. Even the much, much slower 7750 is ahead by 12%, meanwhile the 7770 is in a class of its own, competing with the likes of the 6870. The 7770 series still trails the GTX 560 to some degree, but once again we’re looking at the proof of just how much the GCN architecture has improved AMD’s compute performance.

Our next benchmark is SmallLuxGPU, the GPU ray tracing branch of the open source LuxRender renderer. We’re now using a development build from the version 2.0 branch, and we’ve moved on to a more complex scene that hopefully will provide a greater challenge to our GPUs.

SmallLuxGPU is another good showing for the GCN based 7700 series, with the 7770 once again moving well up the charts. This time it’s between the 6850 and 6870, and well, well ahead of the GTX 560 or any other NVIDIA video cards. Throwing in an overclock pushes things even farther, leading to the XFX BESDD tying the 6870 in this benchmark.

For our next benchmark we’re looking at AESEncryptDecrypt, an OpenCL AES encryption routine that AES encrypts/decrypts an 8K x 8K pixel square image file. The results of this benchmark are the average time to encrypt the image over a number of iterations of the AES cypher.

Under our AESEncryptDecrypt benchmark the 7770 does even better yet, this time taking the #2 spot and only losing to its overclocked self. PCIe 3.0 helps here, but as we’ve seen with the 7900 series there’s no replacement for a good compute architecture.

Finally, our last benchmark is once again looking at compute shader performance, this time through the Fluid simulation sample in the DirectX SDK. This program simulates the motion and interactions of a 16k particle fluid using a compute shader, with a choice of several different algorithms. In this case we’re using an (O)n^2 nearest neighbor method that is optimized by using shared memory to cache data.

It would appear we’ve saved the best for last, as in our fluid simulation benchmark the top three cards are all 7700 series cards. This benchmark strongly favors a well organized cache, leading to the 7700 series blowing past the 6800 series and never looking back. Even NVIDIA’s Fermi based video cards can’t keep up.

Civilization V Theoretical Performance
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  • chizow - Sunday, February 19, 2012 - link

    Those who do not learn from history are doomed to repeat it.

    There's a reason we look at the past, because chances are, what's already in your rig performs the same or better than what AMD is trying to sell you at the same or higher price than what you paid "in the past".

    Everyone needs to set the bar for themselves in terms of what they are willing to pay for an "upgrade", and given there is negative scaling with these parts, its pretty obvious they fail on all fronts. But hey, even you acknowledge this.
    Reply
  • Galidou - Tuesday, February 21, 2012 - link

    Those with a choosen side should not try to explain whatever the history tells us because they have a biased opinion. They can't see both side of the medal as objectively possible as someone with an impartial view and form the beginning you've proven to be on nvidia's side.

    End of the discussion, you can try to explain history but it's YOUR perception. I never said history wasn't worthy of anything the thing is you always are on the same side which means it's worthless from the very beginning.
    Reply
  • Galidou - Tuesday, February 21, 2012 - link

    I do not think it's a TOTAL fail, the 7970 and 7950 isn'T very well priced, but it's not a fail like those. From your point of view a fail is from historical pricing. From my point of view and ALWAYS was like that, it's from a performance/price standpoint and I won't change because you tell me we should look at everything things from the past. Sure we can learn from it.

    There was once a man that beleived the earth was round. But the historians and everyone else beleive it was flat so they killed him. No need to put names in there... History used as an argument makes that sometimes.... You've got to renew your point of view else, you can't see further from what you know.

    AMD is trying to sell you at the same or higher price than what you paid "in the past".

    Like we said before, nothing new here, it's always the same with x2 parts from last gen for years now... And it's only an example from many others of rebranding older designs selling at higher price point which AMD and Nvidia are both strong at.
    Reply
  • Galidou - Sunday, February 19, 2012 - link

    The price is a failure from my perception, 7770 and 7750 is a big fail..... Unlike 7950 and 7970 non-attractive price/performance but still a little justified by it's performance compared to parts that are out NOW and not compared to freaking history of pricing or future video cards...

    People out there will buy the 7770 and they'll be totally satisfied for as long as they'll own the thing. If you spent 4 hours on the internet looking at video card prices and benchmarks and realize you're way better off with a 6850 you might find it a bargain. But for others, if you tell them what you did to get to that conclusion, they'll maybe end up being happy with their choice without searching because they had 4 hours of playtime outside on a sunny day and that's worth it, while you're on the computer looking to spend your money on the best you can find.

    So in the end, whatever we might say, perception is the key in life, we can take a whole day speaking about that and in the end, everyone will be right, because each of us create it's reality by thinking and seeing it the way THEY want... You want to live in the past and the future analyzing everything, you'll end up loosing the present which is the only thing that exists...
    Reply
  • chizow - Sunday, February 19, 2012 - link

    Yes Rarson, its proof stupid people have low standards and will buy anything. How's your 7700 treating you?

    Plenty in stock actually: http://www.newegg.com/Product/ProductList.aspx?Sub...
    Reply

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