[Cbe-oss-dev] Call/return from PPE to SPE functions

[Arnd Bergmann]

On Tuesday 29 May 2007, Julio M. Merino Vidal wrote:
> > 1. saved and idle
> > 2. saved and trying to run
> > 3. loaded and running
> > 4. loaded and idle
> 
> Not exactly related to this, but I want to make sure I understood the  
> code correctly.  Suppose a context A in state 4.  Then you put B1..BN  
> contexts (where N = number of available SPUs) in state 3.  In that  
> case, context A goes to state 1

right

> until it can be rescheduled again   
> (e.g. one of the Bi contexts terminates), at which point it is put in  
> state 2 and later in state 3.  Right?

not exactly. A remains in state 1, until it tries to run again. At that
point, it either goes into state 2 or 3, depending on whether there are
any free (no context loaded) or idle (with a context in state 4) SPUs at
that time.

It also depends on whether any of the threads use real-time priorities,
meaning that they will immediately suspend another context in order
to run, if their priority is high enough.

	Arnd <><