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-   -   Fast Mersenne Testing on the GPU using CUDA (https://www.mersenneforum.org/showthread.php?t=14310)

nucleon 2010-12-10 23:17

[QUOTE=CRGreathouse;241092]I'm seeing 181 watts for the i7 under load. So for your claim "Even when comparing power needed per primality test, they are less efficient than core i7's and other recent CPUs" to hold, the GTX 295 needs to be less than 2.7 times faster than the i7 -- or 10.8 times faster than a single (physical) core. Is that so?[/QUOTE]

My 460GTX does 3.7GHz-days per _hour_ of TF, or 88.8 GHz-days per day.

My core quad-core i7-930 (by my estimation) does 12GHz-days per day all cores utilized.

My GPU is at least 7times faster than my CPU running TF. Scaling the figures presented on the new gpu CUDA code a GTX480 looks like being 4times faster than my cpu on LL testing*.

I haven't checked power consumption fully populated.

-- Craig
*Take the 4times figure with a grain of salt. Large margin of error. Lots of assumptions and no way I can verify this figure for me personally.

ckdo 2010-12-11 00:25

[QUOTE=nucleon;241166]My 460GTX does 3.7GHz-days per _hour_ of TF, or 88.8 GHz-days per day.[/QUOTE]

That's lowish. My MSI N460GTX HAWK does around 107 GHzd/d on a Q6600 while the CPU is running 4 LLs on exponents in the 41M range (bad idea, I know). All at stock speed, that is, and with X fully responsive. There's probably plenty of room for improvement on my end.

nucleon 2010-12-11 04:27

I think it's the win7 gui. I have the full aero interface enabled.

As I move around to certain objects onscreen, I see the rate drop.

-- Craig

Brain 2010-12-12 10:52

Back to hardware
 
Assumption 1: The GTX 460 has lost almost all advanced computing features / double precision support (compared with 470/480)!?
Fact 1: The GTX 470/480 have only 25% of their possible double precision throughput (ref [URL="http://forums.nvidia.com/index.php?showtopic=164417&view=findpost&p=1028870"]here[/URL]) to protect the Tesla cards.

I always thought DP support was mandatory (for LL)?

Please check my facts and give me a hint what kind of graphics hardware fits Mersenne's needs best. ;-)

I my opinion, we do not need more power on the TF part. I'd really love to see CUDA P-1.

cheesehead 2010-12-12 21:34

[QUOTE=Brain;241414]
I always thought DP support was mandatory (for LL)?[/quote]Yes, number of guard bits required renders SP too inefficient.

[quote]I'd really love to see CUDA P-1.[/QUOTE]Yes!

But how much memory is available for stage 2? My sparse understanding about GPUs is that some have on-board RAM, while others (or all) use some of main RAM. Would transfer speeds in the latter case be a bottleneck?

Mr. P-1 2010-12-12 22:07

[QUOTE=cheesehead;241470]But how much memory is available for stage 2? My sparse understanding about GPUs is that some have on-board RAM, while others (or all) use some of main RAM. Would transfer speeds in the latter case be a bottleneck?[/QUOTE]

If that's a problem, then just do stage one on the GPU.

Mini-Geek 2010-12-12 22:57

[QUOTE=cheesehead;241470]But how much memory is available for stage 2? My sparse understanding about GPUs is that some have on-board RAM, while others (or all) use some of main RAM. Would transfer speeds in the latter case be a bottleneck?[/QUOTE]

All GPUs that would likely be used for CUDA work (I'd be jumping to conclusions to say "all CUDA-capable GPUs" - but I think it's practically that) are parts of discrete graphics cards, (as opposed to integrated to the motherboard or CPU) which always include on-board RAM. E.g. a current good pick in the $200 range is a GTX 460 GPU on a card with 1 GB of RAM. I don't see any reason, in principle, why most of this memory can't be used for P-1 stage 2.

Andrew Thall 2010-12-13 17:38

@Brain: Fact #1 is true but irrelevant. LL needs the double precision only for the FFT squaring; as I mentioned before, I get better timings from the Tesla 2050 over the GTX 480 only if I overclock it to the same core-processor speed (1400 MHz); otherwise, the greater number of processors on the GTX more than makes up for the better double precision performance. Surprising, but FFTs have to move a lot of data, too; don't assume that they're time bound by the double-precision multiplies, particularly with the way smart compilers reorder operations to get maximum hardware utilization.

KingKurly 2010-12-13 19:16

I take it that if I want to get in on this fun, I'll have to replace my ATI Radeon HD 5450 that came with my store-built PC? The AMD Phenom II X6 in it is doing great, but this GPU computation looks very promising and interesting. Obviously the ATI card is not going to do CUDA, that much I am aware of.

The machine is currently headless and primarily used for GIMPS. I guess I would be in the market for a new Nvidia card and perhaps a new power supply? (I'll have to look at what's in there, I haven't the faintest clue.)

Brain 2010-12-13 20:43

GTX 560
 
[QUOTE=KingKurly;241653]The machine is currently headless and primarily used for GIMPS. I guess I would be in the market for a new Nvidia card and perhaps a new power supply? (I'll have to look at what's in there, I haven't the faintest clue.) [/QUOTE]

I read first reviews on Nvidia's new GTX 5XX series. They seem to have done a very good job and a lot better than for GTX 4XX. But a 550W system power supply for a GTX 570 ([URL="http://www.nvidia.com/object/product-geforce-gtx-570-us.html"]ref[/URL]) is too much for me. Latest rumors say its small brother GTX 560 will arrive in late January 2011. That one could become best choice (depending an CUDA cores / capabilities).

[QUOTE=KingKurly;241653] I take it that if I want to get in on this fun, I'll have to replace my ATI Radeon HD 5450 that came with my store-built PC? The AMD Phenom II X6 in it is doing great, but this GPU computation looks very promising and interesting. Obviously the ATI card is not going to do CUDA, that much I am aware of. [/QUOTE]

I own an ATI 5770. --> No CUDA. :sad:

ixfd64 2010-12-29 04:05

Hmm, it's been over two weeks since was any update. I hope this doesn't get swept under the rug.


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