Re: [PATCH] RT: Add priority-queuing and priority-inheritance to workqueue infrastructure

[Daniel Walker <dwalker@mvista.com>]

On Wed, 2007-08-01 at 11:19 -0400, Gregory Haskins wrote:
> On Wed, 2007-08-01 at 08:10 -0700, Daniel Walker wrote:
> 
> > 
> > rt_mutex_setprio() is just a function. It was also designed specifically
> > for PI , so it seems fairly sane to use it in other PI type
> > situations ..
> > 
> 
> Yes.  It is designed for PI and I wasn't suggesting you shouldn't use
> the logic itself.  What I was suggesting is that dealing with an API
> that has "rt_mutex" in it for something that has nothing to do with
> rt_mutexes is, well...

It's fine for now .. One step at a time..

> All I was suggesting is that we break out the PI subsystem from rt_mutex
> code so its an independent PI API and have the rt_mutex subsystem become
> a user.   That's a far cleaner way to do it, IMHO.

The workqueues don't really need full blown transitive PI. So without
that your back to the rt_mutex_setprio function .. Which could be
renamed ..

Here was my attempt years ago , 

http://lkml.org/lkml/2005/5/31/288

Looking back on it, I'm not sure what users I was planning to implement
along with it .. I'm sure I was thinking "There must be other blocking
primitives that could use this.." , but now I don't think there are ..
Everything pretty much runs through the rt mutex.. workqueues are just
"dancing" , or changing priorities up/down which is really only the
lowest level of what the rt-mutex does.

Daniel