ext maemo-users-bounces at maemo.org wrote: >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! > > This is a good point. >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 >design! > > Fortunately memorybus is not utilized for graphics all the time. We have a separate LCD controller chip which takes care of refreshing the LCD screen. Memorybus is used when we transfer data from framebuffer in system memory to framebuffer in LCD controller chip (when something needs to be updated). >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! > > Actually, memory *is* a problem in the 'desktop world' aswell, especially with laptops ... swap should not be considered as 'solution' because disk IO is slow. Application developers should just wake up and fix the issues there. I hope that some of Maemo efforts in memory saving will make their way there. >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 > > // Tapani
