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Old 2014-07-12, 16:33   #1
(loop (#_fork))
fivemack's Avatar
Feb 2006
Cambridge, England

644110 Posts
Default 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 auto-detected as 'neon' which the rest of the configure didn't understand), but after about an hour it's running gmp-ecm.

Not especially fast:

echo "(10^71-1)/9" | ecm -c 1 1e6
takes 8.5 seconds on one CPU (also 8.5 seconds on each CPU if you run four in parallel), so five times slower than one core of i7/4930K, but twice as fast as the ODROID Cortex-A9 that I had previously. Comparing with a more realistic competitor, one core of Avoton C2750 takes 4.7 seconds; obviously 64-bit arithmetic is really useful for ECM!

There is a quite capable GPU, but I haven't found a build of the nVidia tools for the Ubuntu-14.04 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 64-bit Cortex-A57 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 16-core 14nm lots-of-Atoms SoC.

For a more serious problem (2340_736),
echo 18140989185283655973469449579704944039975362878755465578374551246406222559010534117329360835005049754874622232679931513368003677417541836205899311159219761141488825676850446673 | gmpecm/ecm-6.4.4/ecm -v -c 1 4e8

Step 1 took 7107196ms
Step 2 took 1387825ms

Last fiddled with by fivemack on 2014-07-12 at 16:40
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