Rainbow cpu load when launching an activity?

[riccardo]

Hi Gary

On Fri, 2008-08-15 at 23:18 +0100, Gary C Martin wrote:
> Hi Michael,
> 
> On 15 Aug 2008, at 21:58, Michael Stone wrote:
> 
> > On Fri, Aug 15, 2008 at 07:31:28PM +0100, Gary C Martin wrote:
> >> I was curious to see (when testing in joyride-2301) that rainbow   
> >> (python /usr/sbin/rainbow-daemon) seems to be the process that's   
> >> eating the most CPU cycles during an activity launch.
> >
> > Well, rainbow does a little bit of work in order to make a new user,
> > then it hands over control to the activity. Since we know that  
> > activity
> > launching is already slow (hence the need for the module preloading
> > hack), it's not very surprising to me to that you see it chewing CPU
> > when launching activities.
> >
> > Feel free to profile, though; I'd certainly like to know it if I'm  
> > doing
> > something truly idiotic. (Or if people are using rainbow in  
> > environments
> > significantly different from my own.)
> 
> Thanks, OK. I'm not exactly fully clued up on profiling such internals  
> but I'll look at instrumenting interesting points of your rainbow  
> source code on a running XO, and seeing if I have something useful to  
> report. Please don't let that put off anyone else more qualified from  
> looking.
> 

Processes spawned by rainbow get their cmdline copied over from
rainbow's one. So I think what you are seeing is that the *launched
activity* is taking more cpu time than the journal and the shell.

The following graph shows browse startup (pid 3612):
http://dev.laptop.org/~rlucchese/temp__browse_warm.svg


riccardo