Re: RSDL-mm 0.28

Andrew Morton
2007-03-11T03:16:36Z

> 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.