[Openmp-dev] [cfe-dev] Implicit/Explicit task yielding in Clang v5.0.0 OpenMP Implementation

[Jeff Hammond via Openmp-dev]

(adding omp-dev; cfe-dev isn't the right place for this, so please don't
copy on subsequent replies)

OpenMP taskyield is useless, by design.  It can be a no-op and there is no
way to guarantee that OpenMP tasks make concurrent progress.
https://github.com/mpi-forum/mpi-issues/issues/75 has some context.  The
OpenMP committee has been discussing this a bunch recently but one proposed
solution was to deprecate taskyield rather than fix it.

I encourage you to discuss your requirements with vendors who supply you
with hardware and/or compilers, since those companies have representatives
in the OpenMP language committee.

Jeff

On Thu, Sep 20, 2018 at 9:39 AM Dawson, Mark via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> While an implementation of OpenMP is **allowed** to insert implicit
> switching points in a task region (i.e., #pragma omp task), I as the
> developer can make use of the standard’s explicit task yielding if need be
> (i.e., #pragma omp taskyield). My question is whether the Clang v5.0.0
> implementation employs such implicit task yielding, or is it necessary for
> me to do so explicitly?
>
> ------------------------------
>
> Confidentiality Notice
> The information transmitted in this electronic mail (e-mail) is the
> property of Belvedere Trading LLC. This e-mail is intended only for the
> person or entity to which it is addressed and may contain material that is
> confidential, privileged or otherwise protected by law. Any review,
> retention, retransmission, dissemination or other use of, or taking any
> action in reliance upon, this information by persons or entities other than
> the intended recipient is STRICTLY PROHIBITED. If you received this e-mail
> in error, please alert the sender by reply e-mail and then delete this
> e-mail and any attachments in their entirety, whether in electronic or hard
> copy format.
>
> All messages sent to and from this e-mail address may be monitored as
> permitted by applicable law and regulations to ensure compliance with our
> internal policies and to protect our business. Emails are not secure and
> cannot be guaranteed to be error free as they can be intercepted, amended,
> lost or destroyed, or contain viruses. You are deemed to have accepted
> these risks if you communicate with us by email.
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>


-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/openmp-dev/attachments/20190314/0966c114/attachment.html>