Re: fairsched + O(1) process scheduler

[Antonio Vargas <wind@cocodriloo.com>]

On Wed, Apr 02, 2003 at 05:10:27PM -0500, Robert Love wrote:
> On Wed, 2003-04-02 at 17:07, Antonio Vargas wrote:
> 
> > Hmmm, we had some way for executing code just after an interrupt,
> > but outside interrupt scope... was it a bottom half? Can you
> > point me to some place where it's done?
> 
> Unfortunately uidhash_lock cannot be used from a bottom half either.
> 
> You can push it into a work queue.  See schedule_work() and the default
> events queue.

I'll take a look.

> > Ok, I did know m68k can do it, but wasn't sure about all other arches :)
> 
> Yep.  Everyone architecture I know of - and certainly all that Linux
> support - can do atomic read/writes to a word.  Thinking about it, it
> would be odd if not (two writes to a single word interleaving?).  There
> are places this assumption is used.
> 
> Anything more complicated, of course, needs atomic operations or locks.

"word == basic unit of transfer from/to memory" on your reasoning, I suppose.

I'm coding this now, hope I can post a basic implementation.

Greets, Antonio.