Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS]

Bill Huey
2007-04-13T21:36:14Z

On Fri, Apr 13, 2007 at 02:21:10PM -0700, William Lee Irwin III wrote:
> On Fri, Apr 13, 2007 at 10:55:45PM +0200, Ingo Molnar wrote:
> > Yeah. Note that there are some subtle but crutial differences between
> > PlugSched (which Con used, and which i opposed in the past) and this
> > approach.
> > PlugSched cuts the interfaces at a high level in a monolithic way and
> > introduces kernel/scheduler.c that uses one pluggable scheduler
> > (represented via the 'scheduler' global template) at a time.
>
> What I originally did did so for a good reason, which was that it was
> intended to support far more radical reorganizations, for instance,
> things that changed the per-cpu runqueue affairs for gang scheduling.
> I wrote a top-level driver that did support scheduling classes in a
> similar fashion, though it didn't survive others maintaining the patches.

Also, gang scheduling is needed to solve virtualization issues regarding
spinlocks in a guest image. You could potentally be spinning on a thread
that isn't currently running which, needless to say, is very bad.

bill