Re: RSDL-mm 0.28

[Con Kolivas <kernel@kolivas.org>]

On Sunday 11 March 2007 14:16, Andrew Morton wrote:
> > On Sun, 11 Mar 2007 13:28:22 +1100 "Con Kolivas" <kernel@kolivas.org>
> > wrote: Well... are you advocating we change sched_yield semantics to a
> > gentler form?
> >
> >From a practical POV: our present yield() behaviour is so truly awful that
>
> it's basically always a bug to use it.  This probably isn't a good thing.
>
> So yes, I do think that we should have a rethink and try to come up with
> behaviour which is more in accord with what application developers expect
> yield() to do.
>
> otoh,
>
> a) we should have done this five years ago.  Instead, we've spent that
>    time training userspace programmers to not use yield(), so perhaps
>    there's little to be gained in changing it now.
>
> b) if we _were_ to change yield(), people would use it more, and their
>    applications would of course suck bigtime when run on earlier 2.6
>    kernels.
>
>
> Bottom line: we've had a _lot_ of problems with the new yield() semantics.
> We effectively broke back-compatibility by changing its behaviour a lot,
> and we can't really turn around and blame application developers for that.

So... I would take it that's a yes for a recommendation with respect to 
implementing a new yield() ? A new scheduler is as good a time as any to do 
it.

-- 
-ck