

Ubuntu on ARM faster than some Atoms? - tankenmate
http://www.phoronix.com/scan.php?page=article&item=ubuntu_1204_armfeb&num=1

======
rbanffy
Interesting.

I use an Atom-based netbook as my home machine and it always felt "fast
enough" (up to the point it hits its disk, which is really slow). Now I want a
new computer.

BTW, the Atom N270 they are benchmarking was launched in 2008. They picked
more or less the slowest Intel processor available.

[http://ark.intel.com/products/36331/Intel-Atom-
Processor-N27...](http://ark.intel.com/products/36331/Intel-Atom-
Processor-N270-%28512K-Cache-1_60-GHz-533-MHz-FSB%29)

~~~
zokier
And the other Intel CPUs are from 2004(!) and 2006. I'm not really sure what
they are attempting to show by using 8 year old CPU as a reference.

~~~
tomflack
It really seems like "what the author had laying around" stuff.

------
willvarfar
All this should be shown in ratio to cost or watts.

------
ChuckMcM
It might have been more accurate to say, "Ubuntu onr ARM now identifiable as
such in the rear view mirror of Intel." :-)

There are a lot of valid comments here that these are ancient ATOM processors.
But it is also valid to say that ARM SOCs have gotten to the point where they
are encroaching on the space, and their makers (TI, BroadCom, Marvell, and
others) are being forced by the demands of the SMARTPHONE wars to make them
actually useful as general purpose platforms.

As a systems guy I see the things that ARM is lacking, a decent IO bus
equivalent to PCI, a memory channel architecture that allows for decent off
chip memory performance with memory modules.

Of course the 'market' for general purpose computers is much smaller than the
market for computers as accessories (tablets, smartphones, laptops) so perhaps
we'll hit a convergence point in the next couple of years.

------
malkia
And the point is? When was the last time you encoded video on mobile device,
when you can off load the process to be done in some automatic batch on your
PC, or online (there are at least 4 such services).

------
sciurus
The ARM chip fares really poorly in the video encoding comparisons. Is this
because of hardware differences, compiler differences, hand-written x86
assembly by the encoder programmers, or something else?

~~~
willvarfar
Its likely an optimisation problem; whilst media playback codecs are often
optimised for ARM, most video/audio capture on ARM devices is encoded by
custom discrete hardware; the encoding of media on ARM using the CPU is likely
not getting the same love as on x86.

------
hackermom
While I am not entirely surprised, this still makes me so happy to see, and
makes me even more positive about a more efficient future of computing through
the ARM core and its ISA. That Atom chip was even clocked 33% higher, and if
my memory serves me right the Atom Diamondville also has a higher IPC than the
current ARMv7.

~~~
Symmetry
_Atom Diamondville also has a higher IPC than the current ARMv7_ I'm not sure
what you mean here. ARMv7 is an ISA, not an architecture, so different ARM
cores that run ARMv7 code, everything from the A5 to the A15, will have
radically different IPCs even though they can have the same set of
instructions for a given program.

And you can't even really compare the IPC of processor architectures with
different ISAs directly, its often easier to solve a problem in one ISA with
less instructions than in a different ISA. RISC architectures often do less
work per instruction than CISC architectures, but ARM has some features like
instruction predication and argument shifting that mean that its individual
instruction are often more powerful than, say, MIPS.

And it is actually fair to compare processor that have different clock rates,
because often the architecture determines how fast a chip you can make.
Itanium servers are only clocked at around half the speed of other
architectures because the ISA is very complex and that's as fast as they can
make them, and so comparing e.g. Power and Itanium processors of equal clock
speed would be horribly unfair to the decisions that Power made that allow
them to clock so high.

So to get a fair comparison you really want to just build the best processor
of a given architecture you can on a given process, and let them fight it out
like they do here. This can be pretty hard to do, since the performance of
different company's processes on a given node can be rather different. I seem
to recall that Intel could put maybe 20% more current through a N-gate on the
65nm node than their competitors, for instance, but using the same process
would be the ideal.

~~~
hackermom
How can you produce such a wall of text over a little misnomer? You obviously
understood that I am referring to the current incarnation of the ARMv7 ISA,
a.k.a the Cortex family.

~~~
Symmetry
Mostly I put up a wall of text because I think the subject is interesting and
I wanted to talk about it, but really there is no one IPC for the Cortex
Family. An A5 will tend to have an IPC that is much lower than an Atom. An A15
will tend to have an IPC that is much higher than an Atom.

And for the cores being compared here, on tight microbenchmarks the superior
execution resources[1] and OoO execution of an A9 will put it ahead of an
Atom, but on pointer chasing code the superior branch predictor of the Atom
will probably give it a higher IPC.

EDIT: [1] Well, really the 16 vs 8 registers, 3 operand instructions, and free
barrel shift in each instruction. I think they have the same number of ALUs
and AGUs.

