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Re: [gomp4] Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading"

From: Bernd Schmidt <bschmidt at redhat dot com>
To: Jakub Jelinek <jakub at redhat dot com>, Thomas Schwinge <thomas at codesourcery dot com>
Cc: gcc-patches at gcc dot gnu dot org
Date: Fri, 22 Jan 2016 14:18:38 +0100
Subject: Re: [gomp4] Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading"
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References: <87r3hac1w9 dot fsf at hertz dot schwinge dot homeip dot net> <569D2059 dot 4010105 at mentor dot com> <87d1subnu5 dot fsf at hertz dot schwinge dot homeip dot net> <87a8nyawph dot fsf at hertz dot schwinge dot homeip dot net> <20160122083625 dot GL3017 at tucnak dot redhat dot com>

On 01/22/2016 09:36 AM, Jakub Jelinek wrote:


I think it is a bad idea to go against what the user wrote.  Warning that
some code might not be efficient?  Perhaps (if properly guarded with some
warning option one can turn off, either on a per-source file or using
pragmas even more fine grained).  But by default not offloading?  That is
just wrong.

I'm leaning more towards Thomas' side of the argument. The kernelsconstruct is a hint, a "do your best" request to the compiler. If thecompiler sees that it can't parallelize a loop inside a kernels region,it's probably best not to offload it.



Bernd

Follow-Ups:
- Re: [gomp4] Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading"
  - From: Jakub Jelinek
- Re: [gomp4] Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading"
  - From: Martin Jambor

References:
- [PATCH] Add fopt-info-oacc
  - From: Tom de Vries
- [gomp4] Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading" (was: [PATCH] Add fopt-info-oacc)
  - From: Thomas Schwinge
- Re: [gomp4] Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading"
  - From: Thomas Schwinge
- Re: [gomp4] Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading"
  - From: Jakub Jelinek

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