[Arm-netbook] Selecting the right Soc for out ARM Notebook project.

[Gordan Bobic]

On 06/05/2012 08:24, krasi gichev wrote:
> OK, so in order have something usable, you had modified yours Toshiba
> with SSD and so on, so this is price add up.

It is perfectly usable to begin with. I modified it because I wanted 
something better.

> And you say that A9 will
> beat atom - probably, but surely not the single core A8 of Allwinner
> A10.

I'm not so convinced. An Atom N450 is single core. Have a look at the 
AES benchmark here between the Kirkwood and N450:

http://www.altechnative.net/2011/05/22/hardware-accelerated-ssl-on-marvell-kirkwood-arm-using-openssl-on-fedora/

A9 is about twice as fast per clock as Kirkwood, and is generally about 
20% faster per clock than A8.

But also note that OpenSSL on x86-64 is built with SSE support in 
assembly, which if done right, should be good for a 4x performance boost 
over doing it without SSE. So ignoring SIMD extensions (SSE/NEON), N450 
is quite likely SLOWER than Kirkwood clock-for-clock.

Note, however, that N450 is a 1.6GHz processor, and there are very, very 
few ARMs that come clocked that high out of the factory. Tegra2 is 
generally only available at up to 1GHz (kernel code suggests up to 
1.2GHz). I find that all of my AC100s clock up to 1.4GHz with minor 
cooling improvements ( 
http://www.altechnative.net/2011/12/31/overclocking-the-toshiba-ac100/ 
), but that is still OC-ing rather than standard, and it is still 
nowhere near the Atom clock speeds (which will no doubt clock higher if 
you really push it - but considering the motherboard TDP seems to be 
nearly 30W to begin with, the wisdom of doing so would be rather 
questionable).

> You need at least nice dual core A9 (or even quad core) to be
> able to compete with atoms (speaking about performance).

I'm not so sure, having used the likes of Efika MX Smartbook. And Atom 
N450 machines. Yes, the N450 is faster, but mainly because it runs at 
twice the clock speed. With a decent single core A8/A9 that can manage a 
more suitable clock speed and decent power management features that 
allow it to drop the clock speeds and core voltages when under-used, it 
would be very comparable.

> Battery life
> will benefit from ARM, that's true. There comes the tablets - you get
> good mobility (battery life + form factor and weight).

Tablets just aren't an option for anything serious. Lack of keyboard is 
not a feature.

> You say that you use T60 - for work I prefer 24" and above screen. You
> cannot convince me that DPI of 1920x1080 of 10-12" screen is usable
> for whole day work.

I find that it is. The issue for me is the pixel count, I don't care how 
small the screen is - nobody has yet made a screen with more pixels than 
my eyes can see. :) The monitor on my desk is an IBM T221 that packs 
3840x2400 onto a 22" panel: 
http://www.altechnative.net/2011/06/05/wquxga-a-k-a-omgwtf-ibm-t221-3840x2400-204dpi-monitor/

> You have your points, just my 5 cents - single core Allwinner A10 is
> not enough for what you want to do. It makes sense if the SoC it at
> least atom-comparable (so say dual or quad core ARM).

That wouldn't be comparable because atoms are generally single or dual 
core at most. So for sensible performance comparison you would compare 
with single or dual core ARMs. Since very few applications actually use 
more than one core, the other cores would just sit idle most of the 
time. And as I explained already, I am reasonably confident that A8/A9 
are already as good as if not better than the Atom N450 clock-for-clock.

Gordan