20140712, 16:33  #1 
(loop (#_fork))
Feb 2006
Cambridge, England
59×109 Posts 
This year's small computer
After a certain degree of fuss (the only EU supplier who had it in stock was SECO in Italy, and more than three months elapsed between order and delivery), my nVidia Jetson TK1 board arrived yesterday. Cost £178.49 including delivery.
Take it out of the box, plug in an Ethernet cable, turn it on, ask your DHCP server which address it most recently handed out, and you can ssh into it without trouble; building GMP6 required explicitly giving armv7l in the system triplet (it was autodetected as 'neon' which the rest of the configure didn't understand), but after about an hour it's running gmpecm. Not especially fast: Code:
echo "(10^711)/9"  ecm c 1 1e6 There is a quite capable GPU, but I haven't found a build of the nVidia tools for the Ubuntu14.04 that is installed on the board; so I have it doing polynomial selection without involving the GPU. Haven't got a spare power meter to work out how much electricity it uses yet; there is a fan, but it's pretty quiet. I imagine next year's small computer will be an AMD Seattle, with 64bit CortexA57 processors, and I wouldn't be amazed if that was more competitive with the Avoton; but nor would I be amazed if Intel brought out a 3GHz 16core 14nm lotsofAtoms SoC. For a more serious problem (2340_736), Code:
echo 18140989185283655973469449579704944039975362878755465578374551246406222559010534117329360835005049754874622232679931513368003677417541836205899311159219761141488825676850446673  gmpecm/ecm6.4.4/ecm v c 1 4e8 Step 1 took 7107196ms Step 2 took 1387825ms Last fiddled with by fivemack on 20140712 at 16:40 
20140712, 18:26  #2  
Bamboozled!
"𒉺𒌌𒇷𒆷𒀭"
May 2003
Down not across
10838_{10} Posts 
Quote:
Four Parallellas fitted with 16core Epiphany coprocessors arrived from Adapteva about 3 weeks ago. Not yet had chance to play with them, partly for lack of connecting gubbins (now largely sorted) but mostly because of Real Life™ issues. The four credit card machines, four USpronged power supplies (one of the connecting gubbins problems here in the UK), four SD cards preloaded with Ubuntu, shipping, sundry baksheesh and a "free" Tshirt cost a total of £463.46  about $790 at the spot rate today. Also got hold of a DEONano FPGA dev kit at about 15% of the above cost. Cute little thing, also CC sized, with no processor at all  unless you want to build one yourself. A 32bit RISC processor is freely available and clocks in at 100 BogoMIPS  roughly five times as fast as my first Linux box. 

20140712, 19:43  #3 
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
2^{4}×3^{2}×41 Posts 
I had a 32bit binary around so I gave it a whirl:
Code:
GMPECM 6.2.3 [powered by GMP 4.2.1_MPIR_1.1.1] [ECM] (10^711)/9 Input number is (10^711)/9 (71 digits) Using B1=1000000, B2=1045563762, polynomial Dickson(6), sigma=3673851391 Step 1 took 2714ms Step 2 took 3370ms Code:
GMPECM 6.4.2 [configured with MPIR 2.5.1] [ECM] (10^711)/9 Input number is (10^711)/9 (71 digits) Using B1=1000000, B2=1045563762, polynomial Dickson(6), sigma=1986288319 Step 1 took 2153ms Step 2 took 2184ms Code:
GMPECM 7.0dev [configured with MPIR 2.6.0, enableopenmp] [ECM] (10^711)/9 Input number is (10^711)/9 (71 digits) Using B1=1000000, B2=1045563762, polynomial Dickson(6), sigma=1:12988648 Step 1 took 1779ms Step 2 took 2168ms 
20140712, 19:59  #4 
"Mike"
Aug 2002
2·3·7·197 Posts 

20140930, 00:06  #5 
(loop (#_fork))
Feb 2006
Cambridge, England
59·109 Posts 
In a moment of lunacy, I ran linear algebra on the Jetson board.
The right options seem to be la_block=8192 la_superblock=98304 (the board has 32kpercore L1 caches and a shared 2M L2 cache over four cores; la_superblock=196608 is about the same speed, 393216 is a good deal slower, la_block=16384 is a lot slower). It takes just under ten hours on four threads for a 1.98M matrix, compared to just over two hours for four threads on i7/4770. Not bad for a machine that fits under an iPad Mini. 
20140930, 00:46  #6  
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
2^{2}·2,381 Posts 
That reminds me of the second most famous quote from Jasper Beardly.
No, not the "That's a paddlin'!" quote. Quote:


20140930, 10:55  #7 
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
2^{4}·3^{2}·41 Posts 
That's quite nice. Have you had a chance to measure power yet?

20140930, 12:48  #8 
(loop (#_fork))
Feb 2006
Cambridge, England
14437_{8} Posts 
Power metering is mostly telling me that USB3 external hard drives are much more serious power hogs that I'd anticipated: 2530W while spinning up, 8W at idle. Will switch around the drives and the devboard tonight and see if I can get some better numbers.

20140930, 19:20  #9 
(loop (#_fork))
Feb 2006
Cambridge, England
59·109 Posts 
Sitting at a command prompt: 3.5W
Running one thread of ECM: 7.0W Running four threads of ECM: up to 13.7W in stage1, up to 14.2W in stage2 Reading the cycles for msieve (from a USB3 drive whose power is not being monitored): 4.0W Making the matrix: 5.5W Constructing packed rows: 3.8W Actual fourthread LA phase: 13.0W 
20140930, 21:18  #10 
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
2^{4}×3^{2}×41 Posts 
That looks like it is possibly slightly more power efficient than a modern pc(quite a bit better than my Q6600).
It is a shame it doesn't have enough memory for large LA jobs or it would be a good machine to leave on a 6 month job. 
20141008, 02:31  #11 
"Mike"
Aug 2002
2052_{16} Posts 

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