Re: luajit on CuBox

[David Given <dg@...>]

On 29/11/12 20:35, Coda Highland wrote:
> The CuBox is pretty nice; I have an older plug computer (the
> DreamPlug, quite a bit more expensive than the CuBox but has 802.11g
> and two Ethernet ports, plus two SD card slots and eSATA) and I can
> tell you that the real attractiveness is that it's small, reasonably
> powerful, and has almost no power consumption -- compared to running a
> desktop computer as a file server, it nearly pays for itself in
> electricity costs over a year.

I used to run cowlark.com off a SheevaPlug --- website, incoming SMTP
plus spam filtering, DNS, file serving, backups, NNTP, etc. I even ran
Java servlets on it. Worked fine and the whole stack including UPS,
external drives and ADSL modem used about 40W. Unfortunately it only had
a single USB port, so storage was a problem. I eventually replaced it
because maxing out the USB port made things a little unstable (the root
filesystem would drop off the USB bus every couple of weeks).

I did look at a DreamPlug, but wanted SATA. I eventually settled for a
custom made machine based on a Mele A1000, nailed to a plank... I have a
rather bad photo here: http://twitpic.com/b9r3n0

Lua-wise, the Plug range doesn't have an FPU, which makes Lua pretty
painful. The A1000 does do VFP but even Luajit isn't that great on it:

dg@anify:~/src/luajit-2.0$ luajit scimark.lua
Lua SciMark 2010-12-10 based on SciMark 2.0a. Copyright (C) 2006-2010
Mike Pall.

FFT        24.12  [1024]
SOR        69.62  [100]
MC         24.76
SPARSE     50.88  [1000, 5000]
LU         35.41  [100]

SciMark    40.96  [small problem sizes]
dg@anify:~/src/luajit-2.0$ lua scimark.lua
Lua SciMark 2010-12-10 based on SciMark 2.0a. Copyright (C) 2006-2010
Mike Pall.

FFT         1.72  [1024]
SOR         3.60  [100]
MC          1.17
SPARSE      2.02  [1000, 5000]
LU          2.34  [100]

SciMark     2.17  [small problem sizes]

I'm actually rather surprised. The A1000 is based on an Allwinner A10
running at 1GHz, which has ARM's own Cortex A8 core; the CuBox has a
Marvell ARMADA 500 at 800MHz in it. Marvell's Kirkwood processors, which
the Plug range use, use Marvell's own cores which are based on the old
Intel StrongARM designs, which are apparently pretty slow and
power-intensive (which is why Intel sold the designs off to them); and
it looks like the ARMADA range is part of the same line. So I would have
expected the CuBox to get less work done per cycle than the A1000. As
this is clearly not the case, Marvell's CPU design departmet seem to
have done some sterling work.

(Yeah, if you're used to the PC world, ARM processors are *insanely*
complicated. I rather miss the days when a 486 was a 486.)

(OTOH we've got some multicore MIPS set-top-boxes in the office that I
*really* drool over...)

-- 
┌─── ｄｇ＠ｃｏｗｌａｒｋ．ｃｏｍ ───── http://www.cowlark.com ─────
│ "Of course, on a sufficiently small planet, 40 km/hr is, in fact,
│ sufficient to punt the elastic spherical cow into low orbit." ---
│ Brooks Moses on r.a.sf.c

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