[cpp-threads] RE: "Agenda" for august 23-25 concurrency meeting

[Alexander Terekhov]

On 8/30/06, Nick Maclaren <nmm1 at cus.cam.ac.uk> wrote:
> "Robison, Arch" <arch.robison at intel.com> wrote:
> >
> > > And historically, almost no algorithms/programs have ever been
> > > found to require such strong guarantees. We once challenged
> > > people to come up with non-toy examples, and never got any.
> >
> > If you have a non-toy example algorithm that shows a need for causality
> > or total store order, I would very much like to see it and show it to
> > our hardware architects.

Talk to your Itanium architects. For some reason, they imposed remote
write atomicity for release stores to WB memory (total store order for
Itanium "semaphores"). There must be something that they had in mind
to justify this restriction, I suppose.

>
> Oh, THAT'S easy!  NO problem.  Of course, if you had asked for a non-toy
> and SANE algorithm, I would have a harder job :-)

Well, most people might get surprised that

http://www.decadentplace.org.uk/pipermail/cpp-threads/2005-September/000610.html

can abort() even with Y and Z being POSIX semaphores (sem_getvalue()
used for loads and sem_post() for stores). But judging from
Linux/glibc sources, that can well be the case.

regards,
alexander.