[Openmp-dev] Enabling OMPT by default

Cownie, James H via Openmp-dev openmp-dev at lists.llvm.org
Mon Dec 18 04:02:08 PST 2017

The ARM folks should chip in. This should clearly be tested on AARCH64 as well!

-- Jim

Jim Cownie <james.h.cownie at intel.com>
SSG/DPD/TCAR (Technical Computing, Analyzers, and Runtimes)
Tel: +44 117 9071438

-----Original Message-----
From: Openmp-dev [mailto:openmp-dev-bounces at lists.llvm.org] On Behalf Of Joachim Protze via Openmp-dev
Sent: Monday, December 18, 2017 11:58 AM
To: Openmp-dev <openmp-dev at lists.llvm.org>
Subject: [Openmp-dev] Enabling OMPT by default

Dear all,

OpenMP 5.0 will introduce OMPT, the OpenMP tools interface. The current 
implementation in the LLVM/OpenMP runtime is at the level of OpenMP TR6, 
as published in November (with some known issues, were we have patches 
under review).
Currently, this feature is deactivated by default (LIBOMP_OMPT_SUPPORT).
According to overhead measurements performed by Intel and on some of our 
machines, this feature introduces a worst case runtime overhead of ~4%, 
but for most cases basically no overhead.
As I understood, some of the build-bots run the tests when the feature 
is enabled. We locally test the changes continuously with different 
compiler versions (icc/gcc/clang), but only on x86_64 architecture.
Further, this feature was tested on ppc64.

How should we proceed to enable this feature by default, and get it 
tested on other architectures?
For the 6.0 release, I would like to enable OMPT at least for the 
supported platforms x86/x86_64 and ppc64.

We would also appreciate collaboration with vendors/users of other 
platforms, to ensure the code is running there.

Typically, only the architecture specific offset needs to be added:

Looking forward to your feedback,

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