[maemo-users] [maemo-users] Re: New software version with VOIP built in - Soon

From: klaus at rotters.de klaus at rotters.de
Date: Mon Feb 20 22:59:40 EET 2006
Am 20 Feb 2006 um 11:08 hat Clemens Eisserer geschrieben:
> Yes I ment UI responsivness, not raw graphic performance.
> The whole UI simply feels a bit sluggish compared to Palms or
> Pocket-PCs, I know they have faster CPUs but i also think their
> software simply is more efficient.

I don't think that there will be a huge speed improvement. Why?

1) The N770 has just a 16-bit data bus but it has to draw the whole GUI to a 800x480 16 bit 
pixel memory buffer. This is much more than the 320x320 pixels on a palm!
2) As far as I understand the OMAP doc, the LCD redraw had also be done using the 16-bit 
memory data path. If its done at 60 Hz (I don't know), there is a constant memory dma at 
800x480x60 = 21,97 MWords/sec blocking the bus. In fact the OMAP has a shared memory 
3) The bus is shared with the ARM cpu core and the DSP cpu core. Of course, there are 
caches, but you can't cache everything.
3) As often said, gtk+2 is very good, but not the fastest. I compiled some demos with fltk, and 
I *feel* that they run faster. But it too late to change the main gui lib and fltk has other 
4) The memory design: The N770 is more or less just a Linux device and uses a lot of 
libraries. Most of the libs are designed for a linux desktop machine, where memory is 
(because of swap) not a problem. This is maybe the biggest problem for Linux based PDAs!
One has to fine tune all those libs to perform better on small devices, which would be a big 
task and maybe also force a development split, so the folks at Nokia must maintain those 
libs. There is no manpower for that.

It would be interessting, how a 128 MB RAM N770 would perform. I think 128 MB-DDR-RAM 
is the limit for the build in OMAP processor.

Don't get me wrong: I like the N770 (especially the bright display!), and I even don't think that 
it is too slow. I compare it with my Sharp Zaurus and most times the N770 wins. The 800 
pixel display is a huge plus working with gnumeric.

Please correct my if there are some facts wrong, I *really* would like to hear that! I got most 
of this reading the OMAP5912 Design Overview, which should be similar to the OMAP1710 
used in the N770 device.

CU, -Klaus
 Klaus Rotter * klaus <at> rotters <dot> de * www.rotters.de

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