[sugar] Performance

[Erik Garrison]

On Thu, Jul 24, 2008 at 06:16:33AM -0400, Greg Smith wrote:
> Hi All,
> 
> I just got word from a decision maker in Uruguay that they are very 
> concerned about "performance". They say that Sugar is slow. I'm probing 
> to get more details but I want to evaluate the options in parallel.
> 
> Focus is on improving this in 8.2.0.
> 
> Here are the areas I can think of:
> - Activity launch time
> I know we had some threads on this but I don't know where we stand. Can 
> I get an update and an evaluation of what it will take to greatly 
> improve this?
> 
> - File/activity open
> Can we improve this? A piece of the latency here may be due to a large 
> Journal being much slower. Can we "chunk" journal reads or otherwise 
> improve the speed of opening files? Can we speed up journal access in 
> its own GUI too?
> 
> - File save
> What is the bottle neck on save? Let's create a test case for this.
> 
> - Task switching
> I've seen some threads on this. Can someone summarize it and give me a 
> hard number to show how we have improved?
> 
> - Hardware
> Can anyone evaluate how much faster it would be with twice the RAM? Is 
> the NAND slowing us down?
> 

My impression is that all of the above areas of user experience are
bound by filesystem io performance and can be greatly affected by
changing the compression scheme which we use on the jffs2 filesystem.
Tests by NoiseEHC (and to a less rigorous extent by myself) suggest that
moving to LZO compression would greatly speed up read and write to the
data store (by at least several times).

The problem with such improvements is that often they require changes in
low-level system compononents.  In the case of LZO compression we would
have to reformat the root filesystem and modify the kernel
configuration.  The simplest way to execute this is via a reflash of an
existing system.

Erik