[Cbe-oss-dev] gang scheduling

[Eric Blossom]

On Wed, Feb 28, 2007 at 01:31:01PM +0100, Arnd Bergmann wrote:
> On Wednesday 28 February 2007, Eric Blossom wrote:
> > Where does "gang scheduling" fit in all of this?
> > 
> > We're looking at using direct SPE -> SPE DMA for part of our GNU Radio
> > port to the cell.  Is there something I have to do to ensure that when
> > my code is scheduled, it's really scheduled across all of it's
> > logically assigned SPEs?
> 
> Gang scheduling is something we have been planning to do for a long time,
> but it's not in this code yet. The interfaces for it are in the code
> though. The idea is that you create a gang directory in spufs and then
> have contexts created inside of it instead of the root of the spufs
> mount point. When the gang scheduling code is in place, the kernel
> will take care of scheduling them all simultaneously.
> 
> Note that the hope is that in many cases that won't even be necessary.
> An application that simply accesses other SPEs as if they were there
> should work the same without gang scheduling, but some operations
> obviously will be significantly slower. Accessing local store memory
> of a sleeping thread has a higher latency because it resides in
> main memory and accessing mailbox or signal notification registers
> will block the current thread until the SPE you access becomes running.
> 
> 	Arnd <><

Thank you.

Eric